“Yes,” said Lady O’Callaghan. She looked serenely over his head for a few seconds and then added: “I’m afraid I cannot help you. I hope my sister-in-law, who is already upset by what has happened, will not be unnecessarily distressed by suggestions that she was responsible in any way.”

“I hope not,” echoed Alleyn blandly. “Probably, as you say, he did not touch the ‘Fulvitavolts.’ When did Miss O’Callaghan bring them?”

“I believe one night before the operation.”

“Was it the night Sir John Phillips called?”

“That was on the Friday.”

“Yes—was it then, do you remember?”

“I think perhaps it was.”

“Can you tell me exactly what happened?”

“About Sir John Phillips?”

“No, about Miss O’Callaghan.”

She took a cigarette from a box by her chair. Alleyn jumped up and lit it for her. It rather surprised him to find that she smoked. It gave her an uncanny resemblance to something human.

“Can you remember at all?” he said.

“My sister-in-law often came in after dinner. At times my husband found these visits a little trying. He liked to be quiet in the evenings. I believe on that night he suggested that she should be told he was out. However, she came in. We were in the study.”

“You both saw her, then?”

“Yes.”

“What happened?”

“She urged him to try his medicine. He put her off. I told her he expected Sir John Phillips and that we ought to leave them alone. I remember she and I met Sir John in the hall. I thought his manner very odd, as I believe I told you.”

“So you went out, leaving the medicine in the study?”

“I suppose so—yes.”

“Did you come across it again?”

“I don’t think so.”

“May I speak to your butler—Nash, isn’t it?”

“If you think it is any help.” She rang the bell.

Nash came in and waited.

“Mr. Alleyn wants to speak to you, Nash,” said Lady O’Callaghan. Nash turned a respectful eye towards him.

“I want you to think back to the Friday evening before Sir Derek’s operation,” Alleyn began. “Do you remember that evening?”

“Yes, sir.”

“There were visitors?”

“Yes, sir. Miss O’Callaghan and Sir John Phillips.”

“Exactly. Do you remember noticing a chemist’s parcel anywhere in the study?”

“Yes, sir. Miss O’Callaghan brought it with her, I believe.”

“That’s the one. What happened to it?”

“I had it removed to a cupboard in Sir Derek’s bathroom the following morning, sir.”

“I see. Had it been opened?”

“Oh, yes, sir.”

“Can you find it now, Nash, do you think?”

“I will ascertain, sir.”

“Do you mind, Lady O’Callaghan?” asked Alleyn apologetically.

“Of course not.”