Kenneth Marshall lifted his head. He said fiercely: “She was also acquitted.”

“She was acquitted,” Poirot agreed.

Marshall said:

“And I’ll tell you this, M. Poirot. Ruth—my wife—was innocent. That I know with complete and absolute certainty. In the intimacy of our life I could not have been deceived. She was an innocent victim of circumstances.”

He paused.

“And I don’t believe that Linda killed Arlena. It’s ridiculous—absurd!”

Poirot said:

“Do you believe that letter, then, to be a forgery?”

Marshall held out his hand for it and Weston gave it to him. Marshall studied it attentively. Then he shook his head.

“No,” he said unwillingly. “I believe Linda did write this.”

Poirot said:

“Then if she wrote it, there are only two explanations. Either she wrote it in all good faith, knowing herself to be the murderess or—or, I say—she wrote it deliberately to shield someone else, someone whom she feared was suspected.”

Kenneth Marshall said:

“You mean me?”

“It is possible, is it not?”

Marshall considered for a moment or two, then he said quietly:

“No, I think that idea is absurd. Linda may have realized that I was regarded with suspicion at first. But she knew definitely by now that that was over and done with—that the police had accepted my alibi and turned their attention elsewhere.”

Poirot said:

“And supposing that it was not so much that she thought that you were suspected as that she knew you were guilty.”

Marshall stared at him. He gave a short laugh.

“That’s absurd.”

Poirot said:

“I wonder. There are, you know, several possibilities about Mrs. Marshall’s death. There is the theory that she was being blackmailed, that she went that morning to meet the blackmailer and that the blackmailer killed her. There is the theory that Pixy Cove and Cave were being used for drug running, and that she was killed because she accidentally learned something about that. There is a third possibility—that she was killed by a religious maniac. And there is a fourth possibility—you stood to gain a lot of money by your wife’s death, Captain Marshall?”

“I’ve just told you—”

“Yes, yes—I agree that it is impossible that you could have killed your wife—if you were acting alone. But supposing someone helped you?”

“What the devil do you mean?”

The quiet man was roused at last. He half rose from his chair. His voice was menacing. There was a hard angry light in his eyes.

Poirot said: