“He looked at Sir John, who was nearest the bed.”

“How would you describe his look? Appealing? Entreating? What?”

“N-no. He—he seemed frightened. It might have been anything. He looked rather like a patient who had been given a drug—morphia, for instance. It’s a kind of frowning stare—I have often noticed it appear when the drug is beginning to take effect.”

“And yet you tell me he had not had anything of the sort.”

“I gave him nothing,” Nurse Graham said.

“There’s a curious inflexion in your voice, nurse. You gave him nothing? Now of what are you thinking?”

She moved uneasily and her face became rather pink.

“I have said nothing about this to anybody,” she told him. “It seemed to me a dangerous thing to speak of what was-was—not absolute fact.”

“Quite right. Don’t you think, though, that you should tell me? Nurse Graham, Sir Derek O’Callaghan was murdered.” He watched her closely. She seemed both startled and shocked. She gave a quick look as if she hoped she had mistaken what he’d said. After a moment he went on:

“He was given a lethal dose of hyoscine. At least four people come under the possibility of suspicion. The very incident you are shying away from might be the one to save an innocent person. I am too old a hand to jump at asinine conclusions. Do you really think you can do any good by keeping me in the dark?”

“Perhaps not.”

“Let me help you. You think, don’t you, that someone had given O’Callaghan something—a drug of some sort?”

“It looked like it, and yet it was too soon for a drug to act.”

“What happened when you returned to your patient? What did you find?”

“You are—very acute,” she said. “When I went back I tidied the room. The patient seemed to be asleep. I lifted his eyelid and he was quite unconscious. The pupil was not contracted. I knew then that he could not have had morphia. Then I saw under a chair by the bed a small piece of white paper. I picked it up and noticed that it had broken pieces of sealing-wax on it. It was certainly not there when Sir Derek was admitted.”

“Have you kept it?”

“I—yes, I have. I wondered then if he had been given anything, and when the room was done out I put the paper into a drawer in his dressing-table. It will still be there.”

“I’ll look at it later on if I may. Who had sat in the chair?”

“Miss O’Callaghan,” she said uneasily.

“And Miss O’Callaghan was alone with the patient for—how long? Three minutes? Five minutes?”

“Quite five, I should think.”

“Notice anything else? Had he had a drink of water, do you think?”

“The glass on the bedside-table had been used.”