"Before proceeding to carry out your plan, you make one last attempt to stir your husband into action. You tell him of your intention to marry Jefferson Cope. Though your husband is terribly upset, he does not react as you had hoped so you are forced to put your plan of murder into action. You return to the camp, exchanging a pleasant natural word with Lady Westholme and Miss Pierce as you pass. You go up to where your mother-in-law is sitting. You have the syringe with the drug in it ready. It is easy to seize her wrist and—proficient as you are with your nurse's training—force home the plunger. It is done before your mother-in-law realizes what you are doing. From far down the valley the others only see you talking to her, bending over her. Then, deliberately, you go and fetch a chair and sit there, apparently engaged in an amicable conversation for some minutes. Death must have been almost instantaneous. It is a dead woman to whom you sit talking, but who shall guess that? Then you put away the chair and go down to the marquee where you find your husband reading a book. And you are careful not to leave that marquee! Mrs. Boynton's death, you are sure, will be put down to heart trouble. (It will, indeed, be due to heart trouble.) In only one thing have your plans gone astray. You cannot return the syringe to Dr. Gerard's tent because the doctor is in there shivering with malaria—and although you do not know it, he has already missed the syringe. That, Madame, was the flaw in an otherwise perfect crime."

There was silence—a moment's dead silence—then Lennox Boynton sprang to his feet.

"No!" he shouted. "That's a damned lie. Nadine did nothing. She couldn't have done anything. My mother—my mother was already dead."

"Ah!" Poirot's eyes came gently around to him. "So, after all, it was you who killed her, M. Boynton?"

Again a moment's pause—then Lennox dropped back into his chair and raised trembling hands to his face.

"Yes—that's right—I killed her."

"You took the digitoxin from Dr. Gerard's tent?"

"Yes."

"When?"

"As—as—you said—in the morning."

"And the syringe?"

"The syringe? Yes."

"Why did you kill her?"

"Can you ask?"

"I am asking, M. Boynton!"

"But you know my wife was leaving me—with Cope—"

"Yes, but you only learned that in the afternoon!"

Lennox stared at him.

"Of course. When we were out—"

"But you took the poison and the syringe in the morning—before you knew?"

"Why the hell do you badger me with questions?" He paused and passed a shaking hand across his forehead. "What does it matter, anyway?"

"It matters a great deal. I advise you, M. Lennox Boynton, to tell me the truth."

"The truth?" Lennox stared at him.

Nadine suddenly turned abruptly in her chair and gazed into her husband's face.

"That is what I said—the truth."

"By God, I will," said Lennox suddenly. "But I don't know whether you will believe me." He drew a deep breath. "That afternoon, when I left Nadine, I was absolutely all to pieces. I'd never dreamed she'd go from me to someone else. I was—I was nearly mad! I felt as though I was drunk or recovering from a bad illness."