“Curious,” said Poirot, his eyes beginning to flicker with the green light I knew so well. “Very curious! They waste much, much time trying to prise it open, and then⁠— sapristi! they find that they have the key all the time⁠—for each of Hubbs’s locks are unique.”

“That’s just why they couldn’t have had the key. It never left me day or night.”

“You are sure of that?”

“I can swear to it, and besides, if they had had the key or a duplicate, why should they waste time trying to force an obviously unforceable lock?”

“Ah! there is exactly the question we are asking ourselves! I venture to prophesy that the solution, if we ever find it, will hinge on that curious fact. I beg of you not to assault me if I ask you one more question: Are you perfectly certain you did not leave the trunk unlocked? ”