Poirot was silent for a moment, then he said gently: “With your permission, I should like to try a little experiment. You have told us all that your conscious self knows, I want now to question your subconscious self.”

“Psychoanalysis, what?” said Black, with visible alarm.

“Oh, no,” said Poirot reassuringly. “You see, it is like this, I give you a word, you answer with another, and so on. Any word, the first one you think of. Shall we begin?”

“All right,” said Black slowly, but he looked uneasy.

“Note down the words, please, Hastings,” said Poirot. Then he took from his pocket his big turnip-faced watch and laid it on the table beside him. “We will commence. Day.”

There was a moment’s pause, and then Black replied:

“ Night. ”