Mrs. Halliday seemed rather reluctant to answer, but at last she said:
“No—he must have taken one small suitcase with him.”
“H’m,” said Poirot thoughtfully, “I wonder where he was that evening. If we knew that, we should know a great deal. Whom did he meet?—there lies the mystery. Madame, myself I do not of necessity accept the view of the police; with them is it always ‘ Cherchez la femme. ’ Yet it is clear that something occurred that night to alter your husband’s plans. You say he asked for letters on returning to the hotel. Did he receive any?”
“One only, and that must have been the one I wrote him on the day he left England.”
Poirot remained sunk in thought for a full minute, then he rose briskly to his feet.
“Well, madame, the solution of the mystery lies in Paris, and to find it I myself journey to Paris on the instant.”
“It is all a long time ago, monsieur.”
“Yes, yes. Nevertheless, it is there that we must seek.”
He turned to leave the room, but paused with his hand on the door.
“Tell me, madame, do you ever remember your husband mentioning the phrase, ‘The Big Four’?”
“The Big Four,” she repeated thoughtfully. “No, I can’t say I do.”