“That’s rather more difficult,” I said slowly. “I shall have to speak as a medical man. Ralph’s nerves must have gone phut! If he suddenly found out that his uncle had been murdered within a few minutes of his leaving him⁠—after, perhaps, a rather stormy interview⁠—well, he might get the wind up and clear right out. Men have been known to do that⁠—act guiltily when they’re perfectly innocent.”

“Yes, that is true,” said Poirot. “But we must not lose sight of one thing.”

“I know what you’re going to say,” I remarked: “motive. Ralph Paton inherits a great fortune by his uncle’s death.”

“That is one motive,” agreed Poirot.

“One?”