“There’s another alternative,” remarked the Chief Constable. “He no doubt had the notes on him. But he may have handed over the formula and opinion to one of his fellow-purchasers.”
“Not to Lansbury,” declared Blick. “He’d have told us.”
“There was a third man,” said the Chief Constable, meaningly. “Von Eckhardstein.”
Blick took two or three paces about the room, thinking.
“I wish we could follow that up!” he exclaimed suddenly. “That fellow’s disappeared, and we’ve done nothing whatever to trace him. How do we know, after all, in spite of his being the wealthy man he’s reputed to be, that for purposes of his own he didn’t shoot Guy Markenmore and appropriate the money and the formula?”
“Possible!” agreed the Chief Constable. “But as to tracing him, we’ve done all we can here, and we’ve ascertained that he hasn’t turned up at any of his usual haunts in London, or in the City. Yet—he’s vanished! Suddenly, too! Now—why?”
Blick paced the room again, thinking still more intently.
“I wonder if Mrs. Tretheroe knows more than she’s told!” he said suddenly. “I’ve a conviction—a sort of intuition—that she does.”
“I’ve had a suspicion of that sort all along,” answered the Chief Constable. “My own personal belief is that I don’t believe her a bit!”
“Well,” said Blick, after more thought, “there’s one thing we can do.”