Pull your trousers up! thought Michael, and immediately, the Cherub bent down and nipped both layers of clothing back into place.

'Did you take anything? Do you remember what it was?'

The mouth hung open, the lips fatter when they were not smiling. Tony's brows clenched, trying to find an answer. 'I didn't take anything.'

'Are you sure? Try to think. What was it called?'

Tony nodded his head solemnly, yes. 'Diclofenac,' he said. 'For my knee.'

Michael was a biologist. Diclofenac was a powerful anti-inflammation drug. Did it have side effects?

'Have you taken it before?'

Tony nodded yes again, like a child.

The wind blew. Like a friend showing up, the train rumbled out of the tunnel. 'This is my train,' said Michael, trying to keep the tone conversational. 'Where are you going, Tony?'

The Cherub replied as if the answer were obvious. 'With you.'

It wouldn't be right to leave him. Michael looked up at the handbag lady and she looked away hastily. The greying man looked miffed that Michael had got there first. Michael pushed his way onto the train as others were getting off, and Tony followed him. Michael clenched the handrail almost as hard as he was clenching his teeth, and looked around him.

Two teenage Indian boys were talking about cars or computers in a jargon he didn't understand. A woman turned over a page of her crinkly newspaper as if toasting its other side, and sniffed delicately. None of them had seen the banquet of Cherub laid out on the platform. Very suddenly, normality closed over them. The doors rolled shut. The noise of the train provided an excuse not to talk, as if it were embarrassed for them.

Tony simply stared, the flesh on his face slack, like old Hush Puppy shoes. There was definitely something wrong with him; he squinted up at the advertising, looking as if ads for Blistex were beyond his mental age. As the train approached Goodge Street, Michael wondered what on earth to do.