You couldn’t miss him. He had the goth/punk look down pat. A body like two pipecleaners tied together. Hair dyed black, sprung in all directions, like an explosion in a coal heap. His clothes were all black, with pins, buckles and obscure band badges scattered throughout. He was filthy. I guessed he had been sleeping rough. I’m pretty sure it wasn’t just the Ritz that would have turned him away.

And he was high.

I’m not a druggy. Far from it. I’ve only had weed once, and as a non-smoker I disgraced myself by puking up. But he was wired. Every movement was jerky, uncontrolled. His head, particularly. His head jerked back and forward, his eyes flicking from side to side. His expression was wild. All fear and nervousness and anger and God-knows-what, all mingled up.

It was late, the carriage deserted. So of course he sat opposite me and nodded. A nod so quick and violent I wondered that he didn’t concuss himself.

I nodded back, and looked away. Great! I must have left the loony magnet switched on. All the carriages he could have picked, and he chose mine.

"Am I being followed?" he hissed. I pretended not to hear.

He kicked my foot, sliding his boot across the floor to do so. So the fairies that were following him wouldn't see, I guess.

"Am I being followed?" he hissed, louder, urgently. He darted his eyes from side to side for me, indicating the directions I should check. The options being, well, one way or the other in the narrow carriage.

I looked both ways. Even better. The carriage was completely devoid of life. The doors hissed closed, and I was trapped inside the carriage with a paranoid drugged-up itinerant.

I shook my head, and cursed myself for not having a paper I could bury my head in. No MP3 player to listen to. Or both. See no nutters, hear no nutters.

He nodded quickly again. "Ah ha, ah ha. Yep. See? You see? I lost them. Yep. I’m the man." His hands drummed arhythmically on his knees, his feet shuffling. Suddenly he screamed, "Too clever for you, aren’t I, you bastards!" and he started giggling, pleased with himself.

I checked my case for my ticket. Well, of course I didn’t. But I didn’t want to pull my laptop case onto my lap without some excuse.

The giggling stopped as though switched off. He looked suspiciously at it.

"Laptop? Yes? Yes? Throw it away. Trust me. That’s how they track you. Chips. Throw it away. That and your mobile. You got a mobile, right? Sure you have. Throw them away. They track you with them. Trust me." Then he started giggling again. "Trust me, I’m a doctor."

Trains, they have CCTV now, don’t they? The emergency lever was a long way away, it seemed to me.

"They tried to get me, yes. Knocked me unconscious with microwaves, woke up in hospital. Bastard doctor was going to put a chip in my head." He leaned forward, screwing his index finger into his temple. "They wanted to put a chip in my head, man. In my head. Can you believe that? Never trust a doctor, man. They’re with them."

He leant back again, feet dancing to an invisible tune, hands fidgeting over his dirty clothes.

"They’re after you too. Oh yes. I hear them." He tapped the side of his head. "In here, through my teeth. I got fillings, yeah? Picks up their radio. I got secrets in here you would not believe."

Silently I concurred. It was highly unlikely I’d believe anything he said.

"They want to find out what secrets I got, then Bam!" He slapped his hands together suddenly, making me start. "You too. They want your secret, and they are not nice. Not nice people at all." He started to wipe his palms on his thighs, as though he had touched something unpleasant. "They’ll torture you for it, oh yes. Down in their secret rooms with no windows and bastard doctors. And you’ll tell them." He was almost weeping now. "You always tell them, eventually."

"Well, I don’t have a secret." I shrugged apologetically.

He looked at me earnestly. "Really? Really? Then you’ve got no hope, mate. They think you do. They’ll torture you till you tell, and if you haven’t got a secret they’ll never stop. Never." And now there were tears in his eyes, his voice reaching that back-of-the-throat whine a kid has when he’s about to wail. "Never stop. Not till they got what they want."

Suddenly he jumped to his feet and bounced to the carriage door, then bounced back, like some marionette on elastic.

"Dump your bag and your phone man. We’ll lose them, here, at the next station. It’s your only hope!"

I shook my head. "Do you think we should be seen together? You leave here, I’ll leave at the next station." The train was slowing. Clever me. Outwitting a mad druggy.

He pondered it, then nodded his head. "OK, Dave. Cool. But dump your stuff, right? And don’t go home. They’ll be there, waiting for you."

The train stopped, and the doors slid open. The goth disappeared down the platform.

Well, that’ll be a story to tell my mates down the pub. Worth a pint, that, at least.

The train stood there, as trains often do. Waiting for a signal. Waiting for a homeward-bound rail employee to finish his cup of tea.

Suddenly my friend reappeared, sprinting back down the platform, past the carriage doors, on out of sight. There followed close on his heels a couple of ticket inspectors. I smiled. So that was his dark secret. He didn’t have a ticket.

Someone boarded the carriage: A man, dark suit, thickset. Some career clerk working late, or fresh from the wine bar. He glanced at me and then looked over my shoulder. As the doors closed I looked over to where he was looking. There was his twin, standing at the other door. He glanced away quickly as I turned, and I thought I saw the suggestion of a wire leading from his ear into his jacket.

Wait…

How had he known I was called Dave?