"Does anybody else know?" he asked.
"Anybody besides Arnold Rent, you mean?" Grey replied. "Well, yes, one other person knows, and that is Ephraim Bark. His information came to him from his sister, who wrote and told him all about the affair when she discovered that she had been made a tool of by Rent and that he did not care two straws for her. We shall know presently how Rent managed to silence that jealous woman's tongue and leave the field clear for himself."
"You mean to say," Tanza began, "that Arnold Rent——"
"My dear fellow, I mean to say nothing. I shall have a repulsive enough task later when I am compelled to speak plainly. Meanwhile, I have told you pretty well all there is to know. We had better go up and see what Arnold Rent is doing. You will not be surprised to hear that he is in Hortense's bedroom, probably looking for papers. Oh, by the way, there is one thing I forgot to mention. It is a photograph I found in the French maid's room. It gave the clue to the greater part of my discovery. Perhaps I had better show it you."
"I should like to see it very much," Tanza murmured.
Grey produced the torn photograph from his pocket and, with the aid of a match, exhibited it to his companion. He would have liked to know who was the other figure in the photograph. But that did not much matter, and it was a point which was not likely to be elucidated. Then the two friends crept quietly into the house. It was not easy to grope their way upstairs in the dark, but they managed it without noise, and presently stood outside the room, watching Rent at work. He seemed to be wrapped up in his task to the exclusion of everything else. He was pacing round and round the room, tapping on the panels and measuring distances with an iron lever in his hand. He was muttering to himself, too, but it was by no means easy to catch what he said. A quarter of an hour passed in the seemingly futile task, and then the searcher appeared to come to some definite conclusion. With a muttered exclamation he drove the point of his lever into one of the panels, and with a crackling, splintering sound the timber gave way. So far as the watchers could see, there was a space behind the panel more or less filled with letters. These Rent stowed away in his pockets. Beyond question, the object of his search was satisfied, for the expression of his face changed and a gleam of gratification sparkled in his eyes. He turned to the door so abruptly that Tanza and his companion had barely time to fall back into the doorway of an empty room before Rent began to descend the stairs. They watched him carrying the candle till he reached the basement of the house.
"What are you going to do now?" Tanza asked.
"Follow him," Grey said curtly. "In point of fact, I promised to take him home. Practically, though behaving like a sane man, the cloud is over his brain still, and I doubt very much if he knows what he is doing. Of course, there is a good deal of method in his madness. Still, we have to deal with a man who is not altogether accountable for his actions."
"And where do I come in?" Tanza asked.
"Oh, you'll go back to the yacht and wait further developments. It won't be very long before I am there again. And when I do come I may bring one if not two visitors with me. It might be necessary to do a little amateur kidnapping, but I am not sure about that yet. And now you had better leave me."