“At least a quarter of a grain. Sir John injected a hundredth, he tells me. Therefore someone else gave the patient a little more than a fifth of a grain—six twenty-fifths, to be exact. It may have been more, of course. I don’t know if the postmortem can be relied upon to account for every particle.”

“I don’t know either,” said Jane.

“There are one or two questions I must ask you.”

“Yes?”

“I’m afraid this is all very distressing for you. You knew Sir Derek personally, I believe?”

“Yes.”

“I’m terribly sorry to have to bother you. Let’s get it over as soon as possible. As regards the anti-gas injection. At the close of the operation Sir John or Mr. Thoms asked for it. Sister Marigold told you to get it. You went to a side table, where you found the syringe. Was it ready—prepared for use?”

“Yes.”

“At the inquest it appeared that you delayed a little while. Why was this?”

“There were two syringes. I felt faint and could not think, for a moment, which was the right one. Then Banks said: ‘The large syringe,’ and I brought it.”

“You did not hesitate because you thought there might be something wrong with the large syringe?”

This suggestion seemed to startle her very much. She moved her hands nervously and gave a soft exclamation.

“Oh! No. No— Why should I think that?”

“Nurse Banks prepared this syringe, didn’t she?”

“Yes,” said Jane.

Alleyn was silent for a minute. He got up and walked across to the window. From where she sat his profile looked black, like a silhouette with blurred edges, He stared out at the darkening roofs. Something about a movement of his shoulders suggested a kind of distaste. He shoved his hands down into his trouser pockets and swung round, facing the room. He looked shadowy, but larger than life against the yellowish window-pane.

“How well did you know Sire Derek?” he asked suddenly. His voice sounded oddly flat in the thickly furnished room.

“Quite well,” she said after another pause.

“Intimately?”

“I don’t know what you mean.”

“Well—did you meet often—as friends, shall I say?”

She stared at his darkened face. Her own, lit by the sallow light from the window, looked thin and secret.

“Sometimes.”

“Recently?”

“No. I can’t see what my acquaintanceship with him has to do with the matter.”

“Why did you faint?”

“I was—I wasn’t well; I’m run down.”

“It had nothing to do with the identity of the patient? It wasn’t because Sir Derek was so ill?”

“Naturally that distressed me.”

“Have you ever written to him?”

She seemed to shrink back into the chair as though he had actually hurt her.

“You need not answer any of these questions if you think it better not to,” he announced. “Still, I shall, of course, go to other people for the information.”