We came back to the dining-room. Poirot had not accompanied us in our tour. I found him studying the centre table with close attention. I joined him. It was a well-polished round mahogany table. A bowl of roses decorated the centre, and white lace mats reposed on the gleaming surface. There was a dish of fruit, but the three dessert plates were untouched. There were three coffee-cups with remains of coffee in them—two black, one with milk. All three men had taken port, and the decanter, half-full, stood before the centre plate. One of the men had smoked a cigar, the other two cigarettes. A tortoiseshell-and-silver box, holding cigars and cigarettes, stood open upon the table.
I enumerated all these facts to myself, but I was forced to admit that they did not shed any brilliant light on the situation. I wondered what Poirot saw in them to make him so intent. I asked him.
“Mon ami,” he replied, “you miss the point. I am looking for something that I do not see.”
“What is that?”
“A mistake—even a little mistake—on the part of the murderer.”
He stepped swiftly to the small adjoining kitchen, looked in, and shook his head.
“Monsieur,” he said to the manager, “explain to me, I pray, your system of serving meals here.”
The manager stepped to a small hatch in the wall.
“This is the service lift,” he explained. “It runs to the kitchens at the top of the building. You order through this telephone, and the dishes are sent down in the lift, one course at a time. The dirty plates and dishes are sent up in the same manner. No domestic worries, you understand, and at the same time you avoid the wearying publicity of always dining in a restaurant.”
Poirot nodded.