Tommy Johnson leaned against the ship's railing, and breathed in the sea air. Life was good.

The weather had been perfect so far - cloudless skies, warm breezes - and tomorrow the cruise would hit its first port. Johnson was looking forward to that: the dusky dolly-birds in the brochure had been inviting. Who would've known so much pleasure could be got out of Why-I-Use-Vigah-Soap-in-25-Words-or-Less? He chuckled. He'd been in the wrong line of work all these years, and hadn't known it.

Folding his sunglasses, Johnson hung them rakishly on the pocket of his white dinner jacket and smoothed back his Brylcreemed hair. That little widow at his table had been giving him the hairy eyeball. He might score. He stubbed out a last cigarette and flicked the end out to sea before heading in to the dining cabin, feeling on top of the world.

Soft lights, clean table linen, sparkling glasses with something sparkling in them - this was the life. Grub was good - his favourite, lobster thermidor. The widow laughed at his best joke, the one about the vicar's wife, and the band was playing the song he liked best - the one he usually got lucky with - 'Stairway to the Stars'. It would be heaven to climb to heaven with you...

He hoped they wouldn't have one of them fancy desserts. He hated fancy desserts. He liked his afters plain and simple and not French. Ahhh... ice cream. Strawberry. His favourite. Perfect. This was a perfect day...

Johnson dropped his spoon, startled. At a distant table, a baby had started crying. Conversation was interrupted for a moment. Then the young mother picked up the child and comforted it, and the meal resumed. But the moment was spoiled for Johnson. Damn kids, he thought. Why do they let the little rats in here? He picked up his spoon again, and savoured his next bite of ice cream... that's odd, tastes funny...

The ice cream really did taste funny. It made Johnson go queer. He looked across the table. The pretty widow was asking him if there was something wrong... there was something wrong, all right. Her smile... it was all crooked, twisted... her face, what the H was wrong with her face all of a sudden? It was... it was melting, that's what it was, and twisting, and...

The whole room wavered for a moment, and then... just disappeared. Damask cloth, gone, replaced by a hard wooden table. Sea view, gone, nothing but blank concrete walls. Charming widow, gone... in her place, a grim-faced warder...

Only the music stayed. And the bowl of melting, poisoned, that's what it was, poisoned, strawberry ice cream... his favourite... Johnson stared at it stupidly.

'That's it!' yelled Moore. 'Computer! Stop program!' The slight whirr of magnetic reels, which the music had masked, ceased. The holographic figures in the projection booth vanished, and an embarrassed-looking warder, dismissed, slunk off outside for a fag. Moore ran his hand over his face in frustration.

'Okay, people, what was it this time? What broke the illusion?'

Parker was the first to speak. 'The child. It was the baby crying. Johnson, er, hates children.'

Moore rolled his eyes. 'How did the child get in there? Babies don't belong at shipboard dinners. Who programmed that?' There were murmurs of denial all around.

Parker cleared his throat diffidently. 'Sir? Er, um... that is to say... Johnson did it himself.'

Moore stared at him. 'Johnson did it himself? JOHNSON isn't HERE, my man. WE are. And Johnson WON'T be here unless we figure out this scenario.' His excitement made him stutter. 'W-w-what do you mean, H-H-Johnson did it h-h-himself?'

Parker the Meek looked as if he might dither himself to death at this point, so his colleague Noonan came to the rescue, waving a print-out sheet at his senior. 'Sir, Parker's right. Johnson is here, in a way. We programmed his responses into the scenario, and the computer came up with this. At the key moment, his vestigial sense that things are going too well for him will set off a search for the catch. Some hidden flaw in the scheme of things. And...' Noonan scanned the printed sheet, '99.9% of the time, the scenario will come up with the baby.'

Moore wrinkled his forehead in perplexity. 'But why a baby?'

Noonan had the answer for this. 'It was the baby crying in the next room that triggered the murders. Johnson thought he was alone with the woman, you see. And then he heard the baby crying... he stifled it with a pillow, and when the woman became hysterical, he strangled her.' He looked pensive. 'They think he might have let the woman live if he hadn't heard the child.'

Moore snorted in annoyance. 'So what do we do?'

Taking his courage into his hands, Parker spoke up. 'Dr Moore, sir? I think I have the answer.' He reached into his laboratory coat and brought out an object, holding it up for inspection. Moore stared at it in disbelief. 'A dummy?'

Parker nodded. 'I, er, have four children. This, um, keeps the youngest quiet.' He cleared his throat. 'I suggest we program into the scenario that the baby is sucking on a dummy containing, er, a small amount of laudanum. Not that we ever do that at home,' he added hastily. He looked to his more confident colleague in supplication. 'We could do that, couldn't we, Charles?'

Noonan nodded. 'It's actually part of Best Practice. My old professor called it "inviting the bad fairy".'

Moore thought for a moment, then nodded briskly. 'Make it so.' He wheeled around in his chair, facing the long console. 'Once more unto the breach, dear friends. And get the lead out. The event is scheduled for tomorrow, and we don't want to disappoint the Home Office.'

As he pushed buttons, made notes, and generally adjusted the scenario, Moore thought to himself, Executions should be painless. The subject should not suspect what is being done to him. Clever idea, that. Clever, and humane.

But who would have thought that the human mind was such a suspicious instrument? If things are going too well, we ask ourselves why...

Moore pushed the last switch into place, savagely. Thomas Johnson, you will die happy. If it takes the last byte of memory I've got.