“I beg your pardon, inspector,” he said at last. “Of course, you have made certain of your facts, but—hyoscine—it’s incredible.”

“You understand that I shall be forced to make exhaustive inquiries.”

“I—I suppose so.”

“In a case of this sort the police feel more than usually helpless. We must delve into highly technical matters. I will be quite frank with you, Sir John. Sir Derek died of the effects of a lethal dose of hyoscine. Unless it can be proved that he took the drug himself, we are faced with a very serious situation. Naturally I shall have to go into the history of his operation. There are many questions which I should like to put to you. I need not remind you that you are under no compulsion to answer them.”

Phillips took his time in replying to this. Then he said courteously:

“Of course, I quite understand. I shall be glad to tell you anything that will help—anxious to do so. I owe it to myself. O’Callaghan came here as my patient. I operated on him. Naturally I shall be one of the possible suspects.”

“I hope we shall dispose of your claims to that position very early in the game. Now, first of all—Sir Derek O’Callaghan, as you told us at the inquest, had been given hyoscine.”

“Certainly. One-hundredth of a grain was injected prior to the operation.”

“Exactly. You approved of this injection, of course?”

“I gave it,” said Phillips evenly.

“So you did. I’m afraid I know absolutely nothing about the properties of this drug. Is it always used in cases of peritonitis?”

“It had nothing to do with peritonitis. It is always my practice to give an injection of hyoscine before operating. It reduces the amount of anæsthetic necessary and the patient is more comfortable afterwards.”

“It is much more generally used nowadays than, say, twenty years ago?”

“Oh, yes.”

“Do you mind telling me just how, and at what stage of the proceedings, it is given? This was not stated specifically at the inquest, I think.”

“It was given in the anæsthetising-room immediately before the operation and after the patient was under the anæsthetic. A hypodermic syringe was used.”

“Prepared, I imagine, by the nurse in charge of the theatre?”

“In this instance, no. I thought this was all perfectly clear, inspector. I prepared the injection myself.”

“Yes, of course—how stupid I am!” Alleyn exclaimed. “That makes it much simpler for me. What exactly did you do? Dip the syringe in a blue bottle and suck up a dram?”

“Not quite.” Phillips smiled for the first time and produced a cigarette-case, “Shall we sit down?” he said. “And will you smoke?”

“Do you mind if I have one of my own? Good cigarettes are wasted on me.”

They sat on two incredibly uncomfortable chairs under the right elbow of the marble woman.