‘Now, M. Martin, you referred to “they” just now. Whom did you mean by “they”?’

‘It was a mere figure of speech used for convenience. I assumed-I don’t know why-a nebulous “they” in the background.’

‘Have you any reason for that belief?’

‘None.’ 

‘You mean you have no conception of who could want you shadowed or for what purpose?’

‘Not the slightest idea. At least-’

‘Continuez,’ said Poirot encouragingly.

‘Ihave an idea,’ said Bryan Martin slowly. ‘It’s a mere guess on my part, mind.’

‘A guess may be very successful sometimes, Monsieur.’

‘It concerns a certain incident that took place in London about two years ago. It was a slight incident, but an inexplicable and an unforgettable one. I’ve often wondered and puzzled over it. Just because I could find no explanation of it at the time, I am inclined to wonder if this shadowing business might not be connected in some way with it-but for the life of me I can’t see why or how.’

‘Perhaps I can.’

‘Yes, but you see-’ Bryan Martin’s embarrassment returned. ‘The awkward thing is that I can’t tell you about it-not now, that is. In a day or so I might be able to.’

Stung into further speech by Poirot’s inquiring glance he continued desperately.

‘You see-a girl was concerned in it.’

‘Ah! parfaitement!An English girl?’

‘Yes. At least-why?’

‘Very simple. You cannot tell me now, but you hope to do so in a day or two. That means that you want to obtain the consent of the young lady. Therefore she is in England. Also, she must have been in England during the time you were shadowed, for if she had been in America you would have sought her out then and there. Therefore, since she has been in England for the last eighteen months she is probably, though not certainly, English. It is good reasoning that, eh?’

‘Rather. Now tell me, M. Poirot, if I get her permission, will you look into the matter for me?’