Kidd took ten minutes to tell a story that could have been distilled into three, but it was worth it. Walking past the Bloxham shortly after eight o’clock the previous evening, he had seen a woman run out of the hotel, down the steps and onto the street. She was panting and looked frightful. He had started to make his way toward her to ask if she needed help, but she was too fast for him and ran away before he could get to her. As she ran, she dropped something on the ground: two gold-colored keys. Realizing she had dropped them, she turned around and hurried back to retrieve them. Then, clutching them in her gloved hand, she had disappeared into the night.

“I said to meself, that’s strange, that is, her taking off like that,” Samuel Kidd mused. “And then this morning I seen police everywhere and I asked one of ’em what was the big to-do. When I heard about these murders, I thought to meself, ‘That could have been a murderer that you saw, Sammy.’ She looked frightful, did the lady—frightful!”

Poirot was staring at one of the many stains on the man’s shirt. “Frightful,” he murmured. “Your story is most intriguing, Mr. Kidd. Two keys, you say?”

“That’s right, sir. Two gold keys.”

“You were close enough to see, yes?”

“Oh, yes, sir—the street’s nicely lit up outside the Bloxham. It was no trouble seeing.”

“Can you tell me anything else about these keys apart from their gold color?”

“Yes. They had numbers on ’em.”

“Numbers?” I said. This was a detail that Samuel Kidd had not revealed to me in his first telling of the story outside the hotel, nor in his second, on the way here in the car. And . . . dash it all, I should have thought to ask him. I had seen Richard Negus’s key, the one that Poirot had found behind the loose fireplace tile. It had the number 238 on it.

“Yes, sir, numbers. Like, you know, one hundred, two hundred . . .”

“I know what numbers are,” I said brusquely.

“Were those, in fact, the numbers you saw on the keys, Mr. Kidd?” Poirot asked. “One hundred and two hundred?”

“No, sir. One of them was a hundred and summat, if I’m not mistaking. The other . . .” Kidd scratched his head vigorously. Poirot averted his eyes. “It was three hundred and summat, I think, sir. Though I couldn’t swear to it, you understand. But that’s what I’m seeing now in my mind’s eye: one hundred and summat, three hundred and summat.”

Room 121, Harriet Sippel’s room. And Ida Gransbury’s, Room 317.

I felt a hollow space open up in my stomach. I recognized the sensation: it was how I had felt when I first saw the three dead bodies and was told by the police doctor that a gold monogrammed cufflink had been found in each of their mouths.