Mr. Ludgrove sat silent for a moment under his friend’s triumphant gaze, a thoughtful frown upon his face. “This is most extraordinary,” he said at last. “If your facts are correct⁠—not that I doubt them for a moment, but I know how fatally easy it is to find presages after the event⁠—it means that both Mr. Tovey and Mr. Colburn received, a couple of days or so before their respective deaths, a white counter bearing a numeral in red ink. It is almost certain that both counters were sent by the same person, and, if they were intended as a warning, we may infer, as you said, that both men were murdered by the same hand.”

Mr. Copperdock nodded rather impatiently. “Just what I told you, all along,” he said.