‘If you knew how to travel through time, would you tell anyone?’ Daniel glanced sideways at his friend and kept walking. He hated it when Justin got weird.

Justin tipped his head back and shook the tic tac box he'd been rattling for the past five minutes over his open mouth. ‘I mean, it wouldn't be much fun knowing something like that and not sharing it, hey? He tossed the box to Daniel who tapped a mint onto his tongue and threw the box back.

Daniel hitched his backpack higher on his shoulders and doubled his pace. Joggers slapped pavement, echoing eerily in the silent street. ‘C'mon, we've got to get away from here before a teacher comes past.’

‘There's this theory, a time travel theory,’ Justin went on, shaking the tic tacs in time with each step. ‘You're into all that SF stuff, right? Time travel, Dan – and you don't even need a machine. Don't tell me you're not interested.’ Justin normally made fun of Daniel's love of science fiction, but there appeared to be no mockery in him now.

They reached the waterfront and crossed the road to the empty beach. The tide was in, lapping listlessly at the dull shore. Wagging school wasn't all it was cracked up to be. If either of them had any money they would be in the games arcade by now.

Daniel dropped his pack and slumped onto the sand, warm despite the overcast sky.

Justin studied the water. ‘It's perfect.’ He turned and fixed Daniel with glazed eyes.

‘Huh?’

‘Perfect for time travelling.’

‘Oh geez!’ Daniel scooped up a handful of sand and flung it at him.

Justin didn't move. ‘Go on, ask, you know you want to.’

‘You're a total attention seeker, you know that?’

Justin dropped to his knees, his face aglow.

Daniel's neck prickled. He glanced at the water. Its brightness made his eyes tear up. Everything was suddenly too bright.

‘I read about it in a book,’ Justin said, spraying spit.

‘You don't read books,’ Daniel said.

Justin's eyes narrowed. ‘Well I read this one. It was about this guy who was flying over the sea one day –’

‘Like Superman?’

‘No, in an aeroplane, you moron. Anyway, he looks out the window and the sea looks like this endless plain, like a mudflat or something, and the guy thinks how if he had a ladder he could climb down and walk on it.’

‘Walk on water. Like Jesus?’ Daniel laughed. The sound was electric.

‘No, you're missing the point. The water wasn't water, it was solid – or at least the guy in the plane imagined it was. Weeks or months later he was driving past a beach, just like this one, on a cloudy day, just like today, and he stopped and stared at the sea remembering how it looked when he was in the plane and the more he stared at it, the more it looked like a solid mudflat. So, you know what he did? He got out of his car and walked across it right into the future.’

Uneasiness crawled up Daniel's spine. He cleared his throat. ‘This book was fiction, right?’

‘Doesn't matter.’

Daniel grinned. Justin almost had him that time. ‘Yeah, it does.’

Justin grabbed Daniel's arm, fingers gouging flesh. His pupils were suddenly as wide as hungry mouths. ‘No, it doesn't because I did it and it's all true. I saw the future, man, saw things you wouldn't believe.’

‘Show me.’

Justin settled back on his haunches. ‘You can do it too, just stare at the sea and concentrate.’

Daniel usually knew when Justin was having a go at him, but this time there was a determination and certainty about him that Daniel had never seen before. Were Justin's words really so crazy?

He stared, and the longer he stared the more the blue-grey surface of the water resembled hills and valleys. His ears filled with the roar of his own blood.

‘Keep your mind open and believe,’ Justin whispered. ‘Remember, you've got to believe.’

Daniel swallowed. His throat was tight, dry. What was wrong with him? He couldn't tear his eyes away from the sea, so familiar, yet now so alien. Justin was right; it really was an endless plain – though not one of mud, but stone.

He stood and walked towards it, away from Justin, past the DANGEROUS CURRENT sign which was the only hint of colour in that grey landscape, and with every step his heart danced and the vision became more solid, more real.

Remember, you've got to believe. Justin's words rang in Daniel's mind. Yes, he would remember, and in believing he, too, would see the future.

With eager steps Daniel ploughed on, not noticing the creeping chill that seemed intent on stealing the breath from his lungs; deaf to the waves breaking on a shore that was now as distant as his own past. He was a time traveller. He was the future, the past, and everything in between. Soon he would have it all.

His mind filled with a swirling darkness that might have been the very fabric of space-time itself – or not. For it was at that moment, as the rip took him and sucked him down, that the illusion turned to vapour and Daniel remembered.

He couldn't swim.