Poirot carried on as if I had not just conceded the point. “Ah, yes, Richard Negus too, he is sitting alone with his drink when the killer pays him a visit. He too says, ‘By all means, drop your poison into my sherry.’ And Ida Gransbury, she is all the while waiting patiently in Room 317, alone, for the murderer to come calling? She sips her tea very slowly. It would be inconsiderate of her to finish it before the killer arrives, of course—how then would he poison her? Where would he put his cyanide?”

“Damn it, Poirot—what do you want me to say? I don’t understand it any more than you do! Look, it seems to me that the three murder victims must have had some kind of altercation. Why else would they plan to dine together and then all go their separate ways?”

“I do not think a woman leaving a room in anger would take a half-finished cup of tea with her,” said Poirot. “Would it not in any case be cold by the time it reached Room 121?”

“I often drink tea cold,” I said. “I quite like it.”

Poirot raised his eyebrows. “If I did not know you to be an honest man, I should not believe it possible. Cold tea! Dégueulasse!”

“Well, I should say I’ve grown to like it,” I added in my defense. “There’s no hurry, with cold tea. You can drink it at a time to suit you, and nothing bad’s going to happen to it if you take a while. There’s no time constraint and no pressure. That counts for a lot, in my book.”

There was a knock at the door. “That will be Lazzari, coming to check that no one has disturbed us during our important conversation,” I said.

“Enter, please,” Poirot called out.

It was not Luca Lazzari but Thomas Brignell, the junior clerk who had spoken up about having seen Richard Negus by the lift at half past seven. “Ah, Monsieur Brignell,” said Poirot. “Do join us. Your account of yesterday evening was most helpful. Mr. Catchpool and I are grateful.”

“Yes, very much so,” I said heartily. I’d have said almost anything to make it easier for Brignell to cough up whatever was bothering him. It was obvious that something was. The poor chap looked no more confident now than he had in the dining room. He rubbed the palms of his hands together, sliding them up and down. I could see sweat on his forehead, and he looked paler than he had before.

“I’ve let you down,” he said. “I’ve let Mr. Lazzari down, and he’s been so good to me, he has. I didn’t . . . in the dining room before, I didn’t . . .” He broke off and rubbed his palms together some more.

“You did not tell us the truth?” Poirot suggested.