Joe looked back at Esi leaning over the water. For a second, he thought she would jump in and swim after him. But she just stood, chest rising and falling, hands balled into fists at her sides. As the punt crawled away up the river, he had the time to see that she didn’t look angry: she looked terrified.

“And what’s this?” Rob resumed in his tour-guide voice, as if nothing had happened. “A spooky Halloween treat for us all. A visit from Joseph Greene! Who, while he may appear to be a living, breathing undergraduate, is in factdead to me.”

Joe smiled uncertainly at the tourists. “Can you drop me off at the Mathematical Bridge on the way back?” he asked Rob in a stage whisper.

Rob ignored his request and pulled directly into the bank. He prodded Joe with the wet, dripping end of the punt pole until hestumbled out. “Begone, foul spirit!” Rob shouted, propelling the punt smoothly back into the middle of the river.

Joe straightened up, hugging the book, and ran.

He took an indirect route back to college, checking constantly over his shoulder. The book was a burning coal against his chest; he didn’t dare look at it, in case what he’d seen had been nothing but an illusion, his mind inventing the future he had dreamt of. As he climbed the staircase, he kept going back, like a talisman, to Esi: her quick, desperate breaths, the terror in her eyes as she had watched him drift out of her reach. If she cared about the book that much, it had to be exactly what it seemed.

By the time he got to his bedroom, his brain was a fuzz of static. He placed what was in his hands down on the desk in front of him.

Poems. By Joseph Greene. His eyes skittered off the words, then came back to rest on them. He felt them settle at his heart, sparking a tiny, glowing light. He lingered on the face of the man on the cover, familiar and uncanny at once: the dusting of silver at his temples, the frown lines between his brows. The eyes of the poet—he couldn’t yet think of them as his own—were focused with single-minded intensity on the woman in his arms. Joe had never looked at anyone like that. It was unnerving, like seeing a picture taken while he was possessed, consumed by a feeling he couldn’t remember.

He touched the slim hardback. It seemed to vibrate, with a potential frantic and invisible as radioactivity. The cover was a promise, but he didn’t know how it would translate into reality. Until he opened the book, everything was possible. He had the strange, superstitious urge to fling it out of the window. But he already knew he wouldn’t. From the moment he had seen it lyingon the road, the only future that existed was the one where he read it.

He took a breath and turned to the first page.

The book began with an Introduction. It was the kind of thing he would usually have skipped—overwritten, academic, promising to “put the poems in context”—but right now, he felt like he needed all the context he could get.

Meant to Bewas a collection of poems about someone called Diana Dartnell. She was an actress, the Introduction told him, the most celebrated of her generation. And she and Joe had been—were going to be—lovers. Epic, till-death-do-us-part, legendary lovers. They would adore each other, and the words he wrote to immortalise that passion would be read, shared, recited at weddings, taught in schools. Remembered. He skimmed over the words, hardly daring to believe it, wanting to with every fibre of his soul.

He turned back to the cover, to the woman who was destined to be his muse. Her graceful black-and-white profile was somehow familiar, as if their souls had already met.

He read on with strange vertigo. The Introduction was a portrait of his life seen from the air, rendered flat and distorted. It talked about a childhood he didn’t recognise, spent in poverty (his parents were solidly lower-middle-class), where his only solace was to roam the Scottish Highlands in search of inspiration (he was from the East Neuk of Fife, sixty miles from the nearest real mountain). It sketched his time at Cambridge with the breathless exuberance of a prospectus, but made no mention of Rob. Diana, of course, had gone to Cambridge too; she would graduate with a 2:2, while he would somehow manage a 2:1. He felt a mixture of surprise and relief. The only other person from their studentyears who merited a mention was Diana’s ex-boyfriend Crispin, to whom she would later be briefly and unhappily married. The implication, that the perfect love story would be interrupted by a breakup and a marriage to someone else, struck a strange, sour note. Reminding himself that the course of true love never did run smooth, he kept reading, scouring the pages to find out when he and Diana would meet—today? Next month? After exams, in the delirious sunshine of May Week? But the Introduction was frustratingly short on details, as if their story was so well-known it didn’t need to be told.

He turned the page to a spread of photographs. Here he was as a student, on crutches with his right leg bandaged. The caption told of a collision with a bike that would happen in his third year (This year, he thought, with a shiver of foreboding), leaving him with a permanent scar. Here, in another photograph, was Diana, the same age or a little younger, arm in arm with a friend at a party. The other girl caught his attention—her expression anxious but determined, the camera flash picking up the dark shine of her skin—but he soon moved on to the last picture, which was of him and Diana together. They were older now, in their midthirties, but their eyes were locked, their hands entwined, as if they were still in the first flush of new love.

He raced through the rest of the Introduction in feverish haste: how his poetry about Diana had catapulted him from relative unknown to national treasure; the awards and honours that had followed; the poems’ enduring legacy as a testament to obsessive love, taking their place in the canon alongside the likes of Shakespeare and Byron (he reread this part several times). Finally, he was heartened to learn that their love story had a happy ending: at the time of writing, he and Diana were still living together in London.

The time of writing.He flicked back to the copyright page.Retroflex Special Edition, it said, with a logo of a capitalRthat looped backwards to draw a second, fadedRbehind it. The year of publication was 2044. He did some quick arithmetic. “Sixty,” he murmured. Here and now, his heart hammering, his blood fizzing in his veins, the idea that he could ever be that old seemed impossible.

He had finished the Introduction. Overleaf were the stark words:

THE POEMS

He turned the page, his heart beating like a countdown.

Those poems aren’t going to write themselves, Rob had said, an hour and several lifetimes ago. But they had. Here they were, laid out on page after page in neatly printed stanzas. And they were good. They were better than good: they were the poems he wished he could write, the ones that always disintegrated somewhere between his mind and the paper. These, miraculously, had made it there intact. The more he read, the more he forgot what he was reading and sank into the poems’ reality: a reality centred around one woman, her beauty woven so vividly through the words that by the end, he longed for her with the rich, impossible yearning you feel for a character in a book.

He closedMeant to Beand sat in the afterglow. He had never been in love, but now he knew how it would feel, and why he needed that experience to write the poems that would realise his potential. The poet wrote about love as a transformation, a tearing apart of the self and remaking it as something infinitely better. He wanted to step into the furnace of that feeling and come out changed into everything he had longed to be.

He opened the book and read the poems again. And again, andagain, until he no longer had to look at the words to hear them resonating inside his skull, as if they had always been there. He wondered if he was the first poet in history to learn his work by heart before even writing it.

And the worry crept in, starting in his gut and working its way up to his fingertips, tingling where they touched the pages. Wasn’t that a paradox? Shouldn’t the space-time continuum be collapsing right now? He lowered the book, half expecting to see the walls dissolving, but they looked as solid as ever. It wasn’t until he caught sight of himself in the mirror, so different from the suave figure on the book’s cover, that he thought of something even worse. By reading about his future, had he inadvertently changed it?

Horror rushed through him. He flung the book away. It hit the edge of the bed and rebounded, falling open. A leaflet fluttered out.

He picked it up. At the top was a drawing of a friendly hourglass with googly eyes, and the headingFREQUENTLY ASKED QUESTIONS.

—Is it really safe to travel through time?

Yes! Stick with your tour guide and follow the terms and conditions, and you’ll be just fine.

—What if I cause a paradox and become my own grandfather?

That’s between you and your grandmother!! But seriously, don’t worry—it’s impossible for anything you do in the past to cause a paradox, becauseanything you do in the past has already happened.