The queue was a pulsing zig-zag of human flesh, stretched around the floor of the entrance hall. Families with bickering children shared space with young couples in t-shirts and crop tops, the baseball-capped chattering of twenty-somethings, the shuffling of trainers, and the gulps of parents swigging from plastic bottles. TVs on the wall displayed grainy images of an archaeological dig that had never happened, the background music an ambient dirge.

Sarah stood in the line and twisted the hem of her skirt. It was hot and she was uncomfortable. Moreover, in queueing terms she was caught between a rock and a hard place: the two friends she had accompanied in the role of gooseberry had got into a disagreement about food some moments ago, and while the argument was more or less done the brooding silence apparently wasn’t. The right person would have been able to break the tension with a joke or a bridge-building platitude. Sarah was not that person, and was thus doomed to wait out the minutes in gloomy, wordless misery.

She concentrated, instead, on the couple in front, imagining their stories the way she did when she was bored. He was dressed a little like an ageing rock star, the rumpled jacket and checked trousers the sort of thing Ozzy Osbourne might pick if he were getting dressed at night during a power cut. His girlfriend was a little more conservative, although the floaty frock was arguably too posh for a theme park.

Sarah stopped herself. Girlfriend? She considered the two of them: the shock of grey hair rising from his head, the way she carried herself like a disgruntled tour manager. Was that who she was? Did they have some sort of bizarre sugar daddy arrangement? Was there a secret room in his house, filled with fetish gear?

Somehow he didn’t seem the type. Sarah tuned into their chatter, which was easy given that Beth and Ollie weren’t talking.

“…or the Masonic Pleasure Paradise on Rishnah Four,” the man was saying. “They have a carnival that goes on for seven weeks. Everyone gets really drunk and then there’s a puppet show where they juggle with kitchen utensils. Why couldn’t we have gone there?”

“I told you,” the woman replied, somewhat testily. “It’s my turn to pick, and I wanted to come to Alton Towers. I’ve not been in years. Rishnah Four can wait a week.”

“Fine. We’ll do that next time, and then we’re doing the waterfalls at Borneo.”

Sarah plugged in her headphones, making a mental note to Google Rishnah and wondering how you got exciting lives like these people had and where she could find one.

*****

Three feet in front, the Doctor was picking at his nails, which prompted a scold from Clara. “Stop doing that.”

“Sorry, mum.”

He peered up the hall. “Why’s it taking so long, anyway?”

Clara was on her phone. “Thirteen’s broken. It’s just round the corner, so everyone comes up here.”

“Thus moving from one queue into another.” The Doctor wore his shark grin. “It’s very British. You should make it a sport. It’d be something else for all the other countries to beat you at.”

She pulled a face. “Says the Scotsman.”

“We’ve been through this. I’m not Scottish. We just share the accent and the dour personality.”

Clara went back to naming Shakespeare plays in her head; it helped keep her temper even. A few minutes passed, the line unmoving. Every so often the doors at the end would open and the next group would filter through and the queue inside the hall would shuffle slowly and ominously forward.

After a time, the Doctor said “So what sort is this? Rails? Centrifugal force? Or is it like that terrifying boat ride?”

“That was In The Night Garden.” Clara had her hand on her hip. “Honestly, what is it with you and Iggle Piggle?”

“Did I never tell you about the time I was out on the Styx?” the Doctor said. “That was a really long week. I had to eat my own shoes.”

“Yeah, but still. The looks we were getting. Also, you didn’t have to sweat quite so loudly.”

“I don’t sweat,” was the reply. “I’m physically incapable of sweating. It’s Time Lord biology.”

“Just don’t make a scene, all right?” Clara muttered. “I really don’t want a repeat of Nemesis.”

“That was ridiculous! The tentacles were completely the wrong colour!”

She had held off playing her final card, but Clara decided the time was right. “The thing is, I came here with my parents. Halloween 2004. It was an early 18th birthday present. This was the last ride of the day. And we all thought it was rubbish, but it was the last time we came here.” She paused. “The last time I came here. Five months later she was dead.”

For the first time in their conversation, the Doctor looked sheepish.

*****

Gareth finished waving the next lot in and then examined the queue. It didn’t seem to be getting any shorter. A steady influx of guests trickled in through the doors at the end of the hall, summer daylight spilling in from outside, casting the people at the back of the line into an ominous multi-limbed shadow that seemed almost to move by itself. Gareth screwed up his eyes and frowned. He’d thought this would be an easy shift, Hex not being the crowd magnet it was in its heyday.

He glanced at his watch, and then up at the two people jostling to the front, pushing past irritated parents and foot-tapping students with the most perfunctory of muttered apologies. Gareth found his bouncer’s instincts kicking in, and it was all he could do to stop himself folding his arms.

“I’m sorry,” he said, “but unless you’ve got a Fast-Track pass or a disability then I’m afraid you’re going to have to go to the back of the queue.”

The man, who looked to be in his 50s, looked at him as if he were someone from another planet. “What? Oh yes!” There was a sudden patting of the pockets – Gareth eyed him warily, and felt an involuntary tension in muscles that were suddenly coiled for action, but instead the man simply pulled out a folded ID card, which he held up for inspection.

Gareth peered at it over his glasses, and then gave a start. “Lord Lucan,” he said. “This is… unexpected.”

“Isn’t it?” said the man claiming to be Lord Lucan, with boyish enthusiasm. “Anyway, you’ll see it’s access all areas, and we’ve got a thing later, so do you mind if we…?”

There was a microscopic pause while Gareth began to process this information, before deciding it wasn’t worth his while. “Yes, of course, of course. Go on through.”

Lord Lucan clapped his hands. “Great! Thank you.” And off he went, the young woman at his side offering an awkward smile of gratitude. “Thanks,” she said. “Can’t miss the… can’t miss the thing.”

The story of what happened to Gareth once he had had time to decompress after this extraordinary set of events is both long and also very interesting, and at some point in the future we may tell it.

*****

“I suppose you’re going to tell me you knew Lord Lucan,” hissed Clara as she and the Doctor made their way to the back of the hall, ready for the next part of the experience. “That you know where he’s been all these years.”

“I didn’t say that.”

“You didn’t have to. In fact – hold on a sec. Was he an alien?”

“Don’t be absurd.” The Doctor was straightening the cuffs on his jacket. “Mind you, his tennis coach was.”

This section of the hall was dark and eerie: a bare, mostly empty chamber of white stone, scaffolding erected here and there to give it the appearance of a building site. What lighting there was made a poor show of things – this was not, the occupants felt, a room that was designed to be looked at, not when there was a television. Said television was actually a large projector screen, square and white and filling much of the top half of the wall at the far end, above the two sets of doors that sat beneath.

Clara shivered. She felt suddenly and inexplicably cold.

The room was filling up now, and it wasn’t long before the lights went out completely and the screen flickered into life, presenting a grainy, blurry woodland track, accompanied by the caption “ALTON, STAFFORDSHIRE, 1821”.

A booming and ominous voice delivered its narrative. “It was on a cold autumn night in 1821 when the thunder of hooves signalled the return of the wealthy fifteenth Earl of Shrewsbury, back to his home… Alton Towers.”

Onscreen: two black horses pulling a carriage, racing through the forest.

The narration continued. “As the journey neared its end, a mysterious figure suddenly appeared in the road. The Earl impatiently demanded of the driver why the carriage had stopped. With palm outstretched, an old woman pleaded with the Earl for a charity of a coin.”

Onscreen: Text, reading like a title card from a silent film. SPARE A FARTHING FOR AN OLD BEGGAR?

“The Earl cruelly dismissed her, and instructed his driver to head back to the towers. Scorned, the old woman screamed a curse: For every branch of the old oak that fell, a member of the Earl’s family would die.”

In the murky darkness, the Doctor cocked his head.

The orchestra swelled, jostling for attention with the on-screen lightning and the booming, increasingly dramatic tones of the narrator. “Later that very same night, a ferocious storm raged, and with one mighty bolt of lightning severed a single branch on the old oak tree. And true to the old woman’s prophecy, a member of the Earl’s family suddenly and mysteriously died.”

The Time Lord was shuffling his feet now. Clara could hear it.

“Shaken by this tragedy, the arrogant Earl ordered his servants that every remaining branch of the oak tree be chained up, in an attempt to prevent further misfortune.”

As the lightning flashed across the screen, Clara glanced to her left. The Doctor was frowning. To be fair, he did that an awful lot – but there were different types of frowns, and while to an inexperienced layman they were all more or less identical, she had learned to read them. The Strange Life Form I Have Yet To Identify frown, for example, had a slightly downturned lower lip, which made it quite different to Heartbreaking Personal Trauma For Someone Else In The Room And For Which I Am Not Emotionally Equipped. And neither of them bore any relation to her personal favourite, There Is A Bad Smell In This Corridor And I Am Reasonably Confident That It Isn’t Me.

It was dark, but she was reasonably confident that this one was There Is Something Awfully Fishy About This Information Dump. Clara sighed. It looked as if Hex would have to wait.

As the video drew to a close, the narrator was waffling on about some bizarre experiments in a secret lab and a battle between science and the supernatural, but the Doctor was already running for the door.

*****

Not many visitors to Alton Towers know about the abandoned toilet block. It’s one of those hidden gems, lying off the beaten track (although not so far off, once you know where to look), dating from the days where the gardens, and not the corkscrews, were the estate’s main attraction. It sits, squat and ugly and uninviting, on a slope of woodland, a remnant from a forgotten age. What little paint remains is flaking to the point of disintegration, the filthy ceramics are cracked and broken, and a chunk of the floor is missing.

Just now it shared the bedraggled clearing with a battered police box that looked like it had seen better days, and it was towards this police box that the two travellers now hurried: the Doctor, nimbly skipping with a spring that defied his physical age, face grim and determined as if remembering that he had left something on the stove; Clara two steps behind, sliding not inelegantly down the slope and feeling grateful that she had decided not to wear heels that morning.

She caught her breath, clutching both sides of a strained ribcage. “Are you gonna tell me what this is all about?”

The Doctor was fumbling for the key. “It hit me like a lightning bolt,” he said. “The chained oak. That’s the funny thing about memories, they never really go away, even when you forget them. They’re like – ” and he swung the door neatly open – “those carnivorous fish that lurk under the water, keeping still enough so that the water looks calm.”

This last sentence had been delivered in one long, concentrated breath as the Doctor strode into the empty TARDIS, the lights in the sentient craft powering up as if to welcome its master, while Clara followed him inside and shut the door behind the two of them. The Doctor surveyed her from across the other side of the console. “Until you stick your hand in.”

“Memories?” Clara’s face was blank. “I don’t – ”

“I keep a diary. Did I ever tell you that? One of those 400 year ones. Gilded edges, embossed pages, leather bookmark. I think I got it in Rymans.”

“You keep a diary?” said Clara, incredulously. “You really don’t seem the type.”

The Doctor didn’t look up from his lever pulling. “And what type is that?”

“You know. Secret thoughts and aspirations. Oh, please don’t tell me you write poetry.”

“It’s not that sort of diary,” the Doctor retorted, with a touch of crabbiness. “It’s more for keeping track. You live this long, you forget things.”

“And people.” Clara had thought she’d kept this low enough so as to be inaudible, and was surprised and a little embarrassed when the Doctor gave her a long, hard stare.

“No,” he said, his face grave. “Never people.”

There was a momentary and vaguely awkward silence while the two of them wondered who should be the one to pick up the thread.

“Anyway,” the Doctor resumed, eventually, “Most of it’s fairly self-explanatory – parasites, alien invasions, manicures, that sort of thing. Except for a single entry that I never really understood, which is probably why it’s been stuck in my subconscious all these years.” He looked up. “It’s all on one line, and it reads ‘Chained Oak’.”

“That was it?”

“That was it. Oh, and one more sentence.” The Doctor had moved round so he was less than three feet away, and his head was very close to hers: if she tilted her gaze very slightly, Clara could see tufts of nasal hair.

She tried not to look. When he spoke again, it was with an ominous calm. “’You’ll know it when you see it.’”

“So what are you saying? You’ve been there before?”

He nodded. “And I think I’m supposed to go back.”

Clara sighed in exasperation. “We can never just visit somewhere, can we?”

“Come on.” Now the Doctor was punching buttons. “Where’s your sense of curiosity? Old tree, unsolved mystery, things that go bump in the night? Besides – ”

He was undercut by a wheezing and groaning that was both familiar and strangely comforting. “Bit of Georgian history. You could work it into the curriculum.”

“God, how many times? I’m an English teacher. Not a history teacher.”

“You’re not?” The Doctor’s brow was unusually furrowed. “Then who am I confusing you with?”

*****

There are short hops and then there are short hops. This particular hop was about 600 metres to the left – frivolous but necessary, the Doctor insisted, because “otherwise we’ll have to go the long way round, and I hate doing that”.

The patch of forestry in which they’d landed was a little more open, a little more accessible, and was graced with a wide and well-trodden footpath that sloped gently uphill. It was a warm afternoon, the sunlight filtering gently through the beeches and pines. There were a few people about, mostly dog walkers enjoying the space.

“I still don’t get it, though,” Clara complained as they stomped up the path. “I mean, it’s a legend. I don’t even think there’s any truth in it.”

“Legends always furnish their backstory from truth,” said the Doctor. “Unless they don’t, which is when they become myths.”

“But the dates don’t add up.” It was true; she remembered reading about it. The legend dated from 1821 or 1840, depending on whom you asked, and there were at least three different versions. Moreover the curse seemed to carry absolutely no weight – the Earl’s bloodline was well-researched and well-documented and there had been no mysterious deaths in the family, at least none that tallied with the chaining of the oak, and none that couldn’t be explained by old age or infant mortality.

“Details.” The Doctor dismissed her protests with a wave of his hand. “So the years may be a bit off. That’s why we’re here, in the present. It’s the best way to get a reading.”

“But still! Witches? Curses? Since when did you believe any of that stuff?”

“I don’t.” The Doctor stopped and rounded on her, and Clara caught herself. He had his calm-but-serious face on, she realised, which meant that you had to listen.

“I don’t believe in witches or curses or magic spells. But it doesn’t mean that nothing happened. Just that there’s an explanation.” He looked her in the eye. “Besides, I’m supposed to be here. You remember? I said so. Some time. In the past.”

Mute, she nodded. The Doctor kept his voice even. “When you’ve lived as long as I have, and you get a message from your past, you listen. Even if it means delaying a pilgrimage.”

Clara shook her head fiercely, fighting to push brewing tears back into their ducts. She managed a low whisper. “That’s a cheap shot.”

“I’m good at them,” said the Doctor, dispassionately. “Shall we go on?”

The tree sat unceremoniously and unannounced up a steep bank. There were no signs and no information panels. There didn’t need to be. It reached up towards the sky like an enormous praying mantis, desperate to reach heaven. Age had bent it, sending the trunk in two directions, while the boughs twisted and curled beneath the weight of the colossal chains that bound them to the forest floor.

Gingerly the Doctor ascended the stone path that led to the tree’s base. He placed one hand on a moss-covered rock to its right, and the other on the trunk, stroking and prodding gently.

“What are you doing?” Clara called from below.

“Finding secrets.” The Doctor whipped out a pair of sunglasses and rested them on his ears. He tapped the left hand side of the frame – a button you couldn’t see without the aid of microscopic equipment – and there was the whirr of a hard drive.

The Doctor examined the information on screen. None of it was good.

“Strange,” he said, half to Clara, half to himself. “This isn’t like any other wood on this planet.”

“When you say ‘wood’, do you mean – ”

“The wood on this tree. Its biowaves are pulsing far faster than they should be. I’d almost say it’s alive.”

“It’s a tree!”

The Doctor stared at her darkly; the effect was somewhat diluted by the sunglasses. “That isn’t what I meant.”

Clara interlocked her arms and walked back and forth, kicking at the ground; it was something she did when she felt suddenly uncomfortable. The Doctor was still fiddling and prodding when he called out “Can you come and have a look at the chains?”

Warily, she ascended to the other side of the trunk, feeling the iron links that hung from a stout branch. The metal was heavy and cold in her hand – no, not just cold, but clammy, almost –

“It’s damp.”

“Yes.” The Doctor nodded. “And it’s the middle of the afternoon and there hasn’t been any rain for three days.”

“So why is it damp?”

The Doctor pocketed his glasses and gave her a boyish smile. “That’s the 64,000 dollar question.”

It was a question that was to be answered sooner than either of them would have liked, in a way that wasn’t exactly ideal, given that the ground suddenly rumbled beneath them.

The Doctor looked down at the soft earth. “Well, I wasn’t expecting that.”

“Doctor,” said Clara, wondering why she was whispering. “I think we should probably go down the steps. Now.”

“Good idea.”

They hurried back to the path; the Doctor’s coat tails whipped as he turned to survey the oak. Incredibly, it seemed to be moving. The base was shimmering, the wood warping and wefting like a sheet on a washing line. The branches shook and wavered – not much, given that they were held by the heavy irons, but visibly. And above, on the boughs, the leaves were rustling and shaking in a manner that betrayed the calm of the windless afternoon; the sound of the ocean in winter, or a monster waking up. Had it not been chained, the tree would have walked.

“God almighty,” muttered the Doctor. “Redfern Dell.”

“What?”

“I’ll explain later. Just don’t get too close to it.”

“Yeah, I think that’s probably sensible.”

The two of them watched as a bough of the tree seemed to twist in its socket. With a noise like nails on a blackboard, it scraped its way out of the trunk, pulling and wrenching itself free, somehow detaching itself from the whole. The chains caught, holding the branch fast, and then seemed to glow, faintly and then reddening, before the metal lost its shape, each link softening and lengthening, as the chain slipped free of its mooring and onto the soft earth below.

Momentarily, the branch folded in on itself. Then, with a bizarre squelch, it was free – and on the ground.

The Doctor blinked. “This is ridiculous.”

“Why is it ridiculous?” Clara was both unnerved and confused. And, for whatever reason, she had gone into Hushed Whisper Mode.

“Sentient trees aren’t my territory. It’s the sort of thing that happens to one of the other fellas. Maybe the skinny one with the coat.” The Doctor’s eyes glanced about him, as if expecting his predecessor to jump out from behind a thicket. “It’s like something out of a fairy story. Next thing you know it’ll be pixies appearing out of a rabbit hole, offering their services.”

“Next thing you’ll be telling me that pixies exist, but they’re actually from another planet or something.”

“Depends on the pixie. Look out!”

While they had been ruminating about pixies, the dismembered branch had rushed them. It had wriggled away from the base of the oak, scrunching and then stretching itself back into shape like a worm, its bark making terrible scraping noises as it went. Then, all of a sudden, it had tilted ninety degrees, turning to face them like a rotating submarine periscope, before suddenly launching itself into space like a torpedo from the same submarine.

It was angled straight at the Doctor’s head.

He only just ducked in time. Unable to alter its trajectory, the branch had shot over the top of his scalp, screaming like an erupting firework. A bank of trees lay straight ahead, but the path was wide and the branch was able to twist in the air before it reached them, turning back on itself in the manner of a physics-defying arrow in some vintage cartoon. All that was needed was a comedy sound effect and some makeshift dust, and the picture would have been complete.

Clara watched the bizarre spectacle unfold with a blend of horror and fascination – unsure whether she should rush the branch, find something to make herself a target, or simply call for help. The branch was pulsing along the ground, slowly but surely advancing on the Doctor like a predatory lion. She looked up: the Doctor had elected to stay more or less where he was, legs slightly apart, bent at the knee, his jacketed arms open as if to try and catch the fallen bough when it inevitably sprang at him.

Mentally Clara assessed her options. Calling for help was not one of them. Rushing the branch was likely to get one or both of them killed. She reasoned that the Doctor would know what this was and likely had the means of dealing with it, but that he was currently unable to do so, given that his energy was being spent evading its attacks. There was only one rational course of action.

She had already picked up the rock. “Hey! Stumpy!”

The rock sailed, and hit its target somewhere across the upper middle, scraping a little of the bark. The animated branch flexed and made a noise a little like a baboon howl. Then it flipped on its side and turned to face its attacker.

The Doctor stared, flabbergasted. “Why’d you do that?”

“Helping you!” She said, backing away a little down the path. “Now do something!”

“I was doing something!”

“Yes, you were getting mobbed by a tree! Now find out what it is so we can get rid of it!”

The branch opened its mouth. Clara gave a start. Seconds ago the branch hadn’t even had a mouth, and then suddenly it did: a red-and-brown chasm lingered inside, adorned with a striking set of wooden incisors. Improbably, some of them appeared to be dripping with what looked like saliva.

Sap, Clara would tell herself later. Right now her priority was to evade the enormous thing that was seemingly about to devour her.

“If you have any ideas,” she said to the Doctor, her heart rising up through her chest so she could feel it beating at the back of her throat, “Now would be a really good time.”

“Just one.” The Doctor was moving clockwise in a wide circle, slowly and carefully. “Come round this way. Let it follow you. Make sure it’s between you and the TARDIS.”

It seemed a ridiculous suggestion. Still, as quickly as she dared, Clara shuffled round the path, her feet crunching on twigs and leaves. The TARDIS was a couple of hundred yards down the track. It looked an awfully long way. The branch, on the other hand, was less than ten feet from her mouth, and getting closer all the time.

“We’re going to duck and run,” said the Doctor.

Clara turned to look at him. “Seriously? Why are you telling it your plan?”

“I don’t think it understands me. It’s just instinct. Ready… now!”

The branch had sprung. Clara threw herself forwards and felt its teeth scrape across the top of her hair, grazing the scalp. She didn’t stop to check for blood. She ran full pelt for the TARDIS door, not daring to look back. Two hundred feet. A hundred and ninety. She could hear the rustling of leaves behind her, a sign that the branch was turning round for another charge. She didn’t dare look back, even to check that the Doctor was following her.

She could hear the firework scream as the branch launched itself once again, and then the Doctor was suddenly in front and his key was scraping tumblers, and the two of them fell through the open door and then slammed it shut upon a very dangerous slab of oak.

*****

Thump. Thump. Baboon. Thump. Clara got up. The TARDIS hummed around her. She made a note of familiar surroundings, blackboards and bookshelves. Gingerly she rose to her feet, smoothing her dress and checking the top of her head for any signs of cranial injury.

Across the room, the Doctor busied himself at the console, jumping between information panels and controls, punching buttons and swiping the touch screen.

He gave her a glance. “You OK?”

“Fine.” She looked at the door. Every few seconds she could hear another thud, then a scrape, then another thud. A howl, another thud. Perhaps, occasionally, a low rumble, something growling through its recently discovered teeth. The door itself showed no signs of giving, but she had to remind herself it was only wood.

Clara frowned. Was it wood? Or something that bore the appearance of wood? She realised she didn’t know. She glanced over at the Doctor, who didn’t seem concerned.

“We’re safe, aren’t we?”

“For the moment, yes. But it’s not going anywhere. Whereas we most certainly are.”

She wandered over to the control panel to join him. “What even is it, anyway?”

He looked up. “First, that’s not a proper sentence, and as an English teacher I’d have expected better from you. Second, it’s a parasitical biohost. A genetically engineered life form programmed to annhilate anything that threatens it. It’s able to invade basic forms of plant life. You’ve read Day of the Triffids?”

She nodded.

“That was non-fiction. Basically, it’s just a glorified computer program, lying in the earth. Best guess, it’s been dormant for some time. At least until now.”

Clara gulped. “Did we wake it up?”

The Doctor resumed his fiddling. “No, it was coming out of hibernation. We just got in the way. As to who put it there… your guess is as good as mine.”

She dabbed at her head with a cloth; it helped with the brain-racking. “Hang on. In one version of the story, the Earl’s son was out riding the next day, and was killed when one of the branches fell on his head. You don’t think…?”

“Who knows?” The Doctor shrugged. “There’s something going on, but right now our priority is getting rid of this thing, before it actually does some damage.”

“You don’t think it’s going to get in, do you?”

The Doctor jammed down his favourite lever. “Of course not. But I’m not having it break the fenders.”

*****

The branch was still clinging to the battered old police box when it dematerialised. It became aware of a displacement, the landscape shifting around itself and then disappearing into a swirling blue haze. From the perspective of anyone observing, the box had vanished from where it had been standing – taking the branch with it – but from the perspective of the branch itself it was more that the forest had faded out of existence, replaced by a mass of black and angry clouds, swirls and non-space, bolts of lightning raining jagged streaks here and there.

The branch had no appreciation of colour or sound, only of its mission: to eat. It resumed its crawl across the surface of the TARDIS as they hurtled through the vortex, grasping and scratching at the corners with its teeth.

It didn’t smell the woodsmoke until it was too late.

*****

As they opened the TARDIS door, the Doctor was struck by a curious sense of deja vu. It concerned another time, another companion, and another creature clinging to the outside of the ship. He smiled in amused recollection, and made a note to tell Clara about it some time, perhaps over coffee.

The two of them lingered in the doorway, gazing out at the daylight. It was early evening, and in the distance the sun was sinking downwards into an autumnal horizon, bathing the grass with an orange glow. Clara looked about her to get some idea of their surroundings: they had moved, it seemed, not just in time but also in space, landing on the edge of a well-kept lawn.

She could smell burning. Around her, a small cloud of ash seemed to dance and spin.

“Is that…?”

The Doctor nodded. “It’s only wood, after all.”

Clara wrinkled up her nose in disgust. “I feel kind of sorry for it. I mean, it was just following instructions.”

The Doctor glanced at her. “That’s what they said at Nuremburg.”

She resisted the urge to punch him, and wandered outside. The Doctor had put on his sunglasses and was taking readings. “Anyway. I think I destroyed it. As to who or what put it there, we may never know.”

“Doctor – “

“There’s one thing that bothers me,” said the Doctor, looking out at the horizon. “I don’t remember encountering it before, at least in this neck of the woods. So how did I know to put it in the diary?”

Clara was pointing. “Do you remember the National Gallery?”

The Doctor turned to see what she was pointing at.

“Oh,” he said, when he saw the second TARDIS.

*****

Time is always relative, but sometimes it’s borrowed. The Doctor knew this more than anything. He stole through the console room, marvelling at how tastes changed. There was a time he felt totally at home amongst these walls. And then there’d be a bright light and a sea change and the ship would reconfigure itself around him, the way that dog owners begin to resemble their dogs. Which one of us, he pondered, is the dog?

Not being discovered: that was the key. He never knew where the note had come from, and thus he knew that he would have to place it unobserved, and leave unobserved, his younger self none the wiser. It was quietly ridiculous. It was also a paradox of fate, and while the Doctor was usually at the front of the queue when it came to challenging fate, he knew that his own history was a hornet’s nest he’d rather not poke.

His eye was drawn to the chest in the corner. He stirred, momentarily struggling to recall the combination. Opened it. Moved aside yo-yos, Sony Walkmans, a signed set of Douglas Adams novels.

Bingo.

Frowning, the Doctor removed the Bingo card, wondering how on earth that had got in there, and was pleased to find the diary underneath. He groped in his pockets for a biro, and leafed the pages.

*****

Clara stood outside, anxious, glancing one way and the other as the light faded.

“I’ve figured it out,” the Doctor had said. “Why I don’t remember writing that entry. And also – ” and he had patted the rim of his own TARDIS, with enough affection to make her just a little bit jealous – “why she’s brought us here. It’s a loop. A loop that still needs tying. No, wait, that’s a knot. Something like that, anyway.”

And now he was inside, closing the loop, and she was keeping watch. The breeze ruffled the grass, and her hair: aside from that the evening was quiet, until suddenly, from a way off, she heard voices.

“And you’re sure it’s gone?”

“Pretty sure, yeah. Absorbed up by the ground, I shouldn’t wonder. Might have to pop back at some point, just to check on it. If I remember.”

“And the Earl, he’ll be – “

“Oh, they’ll all forget. They usually do. Few weeks, it’ll be like nothing ever happened. Now come on. Places to be, planets to rescue. Onwards.”

Clara smiled; it was a hybrid smile, caught somewhere between nostalgia and melancholy. Then she remembered her job. Rapped on the TARDIS door. Once, twice, three times.

*****

“Do you think he saw us?”

“Said the cavemen of the myopic dinosaur.” The Doctor looked up from his tinkering, allowing himself the luxury of the anachronism. You could always forgive an anachronism when there was a pun involved.

“No,” he said, putting down the fragments of toaster and wandering over to Clara, who was still staring absent-mindedly at the TARDIS door, as if expecting someone to walk through it at any moment. “He didn’t because I didn’t.”

“But you remember being here.”

“I do. I remember it all. An apparently unconnected escapade… oh, a lifetime ago, in more ways than one. The uncharitable Earl, the lightning, the demonic geese… I mean, it was fun. All that said, I had no idea that I was here. And thus we pop in and out of the thread, unseen, unsensed, vanishing without a trace.”

“For the sole purpose of leaving a note.”

“Precisely.” The Doctor steepled his fingers and grinned at her. “Ninjas with pens.”

“So what now?” She had her hand at her hip again. Inwardly, the Doctor sighed. They had been through a lot together and he could read her body language even better than she could read his. Travelling with Clara was wonderful, but sometimes she had expectations.

He decided to indulge her. “We go back – well, forward, I ought to say. I’ll hit the fast return and we’ll be just where we were. And then you and I are riding Hex. Properly, this time.”

“You know, we really don’t have to – “

“Yes. We do.” The Doctor moved round from the console so that he was standing quite close, almost but not quite within touching distance. “Because there’s a time for chasing the monsters in the dark, and a time for paying your respects.”

She smiled. “Thank you.”

“We’re good?”

“We’re good,” said Clara. “Can we do the Smiler afterwards?”

“Only if I can sit at the front.”

“Fair enough.”

He hit the switch, and they were gone.

For Josh, who helped fix it.