"It seems that she knew how Agstone was wanted for certain other murders in the South Seas," said Martaban, glancing at the papers, "so she threatened to have him extradited unless he did her bidding. He was, I regret to say, quite willing to do so, as he hated Sir Oliver, who treated him like a slave."
"That," said Prelice emphatically, "I also know from Brisson. And then?"
"Then when Mr. Haken retired, Sir Oliver burned the herb in a shallow bronze cup—the same as Mr. Shepworth saw in his flat—and went into a trance. Madame Marie had arranged with Agstone that he should watch at the window until Sir Oliver was insensible, and then kill him. The man did so with the jade-handled paper-knife."
"Why wasn't Agstone stifled with the smoke fumes?"
"Because the smoke had died away. When Sir Oliver was dead, Agstone heard a step, and, after setting fire to some more leaves, he ran out of the window, not the one opened by Miss Chent, but another one. He watched, and saw Miss Chent enter; saw also how she fainted with the acrid smoke. He entered, and placed her in the armchair where she was found. It was then that Madame Marie came downstairs and into the room. She snatched up the third will, at which Sir Oliver had been looking, before manipulating the herb, and tearing it up, flung it into the fire. Then she gave the will leaving everything to Miss Chent—which Lanwin had also been looking at to destroy, I presume—to Agstone, and told him to take it up to his brother, Dr. Horace."
"What for?" asked Prelice, surprised.
"Madame Marie said she had no grudge against Miss Chent," explained Martaban, "and wanted the will placed safely out of Jadby's way, so that Miss Chent might inherit, and that Jadby might be kept poor."
"One for Mona and two for herself," said Prelice grimly. "But who placed the knife in Mona's hand?"
"Agstone, who hated her, did. A step was heard—that was Shepworth coming down—so Madame Marie ran out of the window, and got back to her room by another door, which Agstone had left open. The man waited to smear Miss Chent's dressing-gown with blood and to place the knife in her hand. Then Mr. Shepworth—so he says—secured the knife, and——"
"I know all that," said Prelice, "and understand the why and the wherefore of the first crime. But the second?"