“Then listen. During the week before the operation I’d been pretty well at the end of my tether. I suppose when a man of my age gets it, he gets it badly—the psychologists say so—and— well, I could think of nothing but the ghastly position we were in—Jane and I. That Friday when I went to see O’Callaghan I was nearly driven crazy by his damned insufferable complacence. I could have murdered him then. I wasn’t sleeping. I tried alcohol and I tried hypnotics. I was in a bad way, Alleyn. Then on top of it he came in, a sick man, and I had to operate. Thoms rubbed it in with his damn-fool story of some play or other. I scarcely knew what I did. I seemed to behave like an automaton.” He stopped short and raised his eyes from the contemplation of his hands. “It’s possible,” he said, “that I may have made a mistake over the first tube. It may not have been empty.”

“Even if the tube had been full,” suggested Alleyn, “would that explain how the tablets got into the measure-glass?”

“I…what do you say?”

“You say that the first tube may not have been empty, and you wish me to infer from this that you are responsible for Sir Derek’s death?”

“I…I… That is my suggestion,” stammered Phillips.

“Deliberately responsible or accidentally?”

“I am not a murderer,” said Phillips angrily.

“Then how did the tablets get into the measure-glass?”

Phillips was silent.

The inspector waited for a moment and then, with an unusual inflexion in his deep voice, he said:

“So you don’t understand the idealistic type?”

“What? No!”

“I don’t believe you.”

Phillips stared at him, flushed painfully and then shrugged his shoulders. “Do you want a written statement of all this?” he asked.

“I don’t think so. Later, if it’s necessary. You have been very frank. I appreciate both the honesty and the motive. Look here—what can you tell me to help yourself? It’s an unusual question from a police officer, but—there it is.”

“I don’t know. I suppose the case against me, apart from the suggestion I have just made, is that I had threatened O’Callaghan, and that when the opportunity came I gave him an overdose of hyoscine. It looks fishy, my giving the injection at all, but it is my usual practice, especially when Roberts is the anæsthetist, as he dislikes the business. It looks still more suspicious using a lot of water. That, again, is my usual practice. I can prove it. I can prove that I suggested another surgeon to Lady O’Callaghan and that she urged me to operate. That’s all. Except that I don’t think— No, that’s all.”

“Have you any theories about other people?”