Colonel Anderson was looking at Mr Downes with a very curious expression.

‘You can consider that you’re a lucky man, Mr Downes.’

‘I do, sir. Not even a palpitation!’

‘You don’t quite take my meaning, Mr Downes. You were sitting two seats away, you say?’

‘Actually I was sitting at first in the next seat to the murdered man—then I moved along so as to be behind an empty seat.’

‘You’re about the same height and build as the dead man, aren’t you, and you were wearing a woollen scarf round your neck just as he was?’

‘I fail to see—’ began Mr Downes stiffly.

‘I’m telling you, man,’ said Colonel Anderson, ‘just where your luck came in. Somehow or other, when the murderer followed you in, he got confused. He picked on the wrong back. I’ll eat my hat, Mr Downes, if that knife wasn’t meant for you!’

However well Mr Downes’ heart had stood former tests, it was unable to stand up to this one. He sank on a chair, gasped, and turned purple in the face.

‘Water,’ he gasped. ‘Water…’

A glass was brought him. He sipped it whilst his complexion gradually returned to the normal.

‘Me?’ he said. ‘Why me?’

‘It looks like it,’ said Crome. ‘In fact, it’s the only explanation.’

‘You mean that this man—this—this fiend incarnate—this bloodthirsty madman has been following me about waiting for an opportunity?’

‘I should say that was the way of it.’

‘But in heaven’s name, why me?’ demanded the outraged schoolmaster.

Inspector Crome struggled with the temptation to reply: ‘Why not?’ and said instead: ‘I’m afraid it’s no good expecting a lunatic to have reasons for what he does.’

‘God bless my soul,’ said Mr Downes, sobered into whispering.

He got up. He looked suddenly old and shaken.

‘If you don’t want me any more, gentlemen, I think I’ll go home. I—I don’t feel very well.’

‘That’s quite all right, Mr Downes. I’ll send a constable with you—just to see you’re all right.’

‘Oh, no—no, thank you. That’s not necessary.’

‘Might as well,’ said Colonel Anderson gruffly.

His eyes slid sideways, asking an imperceptible question of the inspector. The latter gave an equally imperceptible nod.

Mr Downes went out shakily.

‘Just as well he didn’t tumble to it,’ said Colonel Anderson. ‘There’ll be a couple of them—eh?’

‘Yes, sir. Your Inspector Rice has made arrangements. The house will be watched.’

‘You think,’ said Poirot, ‘that when A B C finds out his mistake he might try again?’

Anderson nodded.

‘It’s a possibility,’ he said. ‘Seems a methodical sort of chap, A B C. It will upset him if things don’t go according to programme.’

Poirot nodded thoughtfully.

‘Wish we could get a description of the fellow,’ said Colonel Anderson irritably. ‘We’re as much in the dark as ever.’

‘It may come,’ said Poirot.

‘Think so? Well, it’s possible. Damn it all, hasn’t anyone got eyes in their head?’

‘Have patience,’ said Poirot.

‘You seem very confident, M. Poirot. Got any reason for this optimism?’