"Of which Osip is guilty?" "Yes, I firmly believe, from the warning sent, that Osip is guilty." "Then you mean to say that Osip went upstairs after killing Horran, released Ferdy, and brought him down to----" "No! no! Osip would not know where Ferdy's room was, and he would not know that he was drunk and locked up. But Ferdy himself might have feigned drunkenness so as to induce me to lock him up." "Had you ever done so before?" "Oh, yes. I punished Ferdy in that way. Besides, I was afraid that, in his drunken mood, he might wander about the house, and perhaps set the place on fire. Ferdy always resented my locking him up. But in this instance, if he was likely to be implicated in a crime, and forced to be an accomplice by the stronger will of Osip, the locked door would provide a convenient alibi. Ferdy might have pretended drunkenness, and then have released himself with another key, and have--done what I said." Anthony did not immediately reply. He stood before Clarice, biting his nails and thinking. "When I went up to town this morning," he said, slowly, "Ferdy asked me to get him any letters that might be waiting for him at Sir Daniel Jerce's place in Harley Street." "Yes. Ferdy lives with him. Well?" "Jerce was away, and had been for some time. Down in Whitechapel, I think the servant said. It was just as well." "Why?" asked Clarice, rising, as Ackworth took three letters from his pocket. "Because he might have seen this especial letter addressed to Ferdy--this letter stamped with the Purple Fern." Clarice took the square envelope he held out. It was addressed to her brother at Jerce's house, and on the flap of the envelope, in purple wax, was stamped a small fern. Few people, unless they looked very closely, would have noticed the fern, and certainly nine people out of ten would not have connected the stamp with the crimes, unless the murders were in their minds. Apparently, the tenth and more observant person was Anthony. "I intend to take that letter to Ferdy, and make him open it in my presence," said Ackworth, "and--oh, Clarice, what are you doing?" "I am opening the letter," said the girl, calmly. "I take all responsibility for doing so, and will tell Ferdy." "Still, it is not quite right to open----" "Not quite right!" repeated Clarice, fiercely, "do you think I care for that when Ferdy's neck may be at stake. I do this"--she opened the letter--"in a most deliberate way, and well knowing what I am doing. Now I shall read it." Anthony could not but admit that Clarice was right, and secretly thought that it would be better for her to read the letter than for the police to scan its contents. She read quietly enough, and then passed it to her lover. "There's a masked ball at the Shah's Rooms to-night," she said, irrelevantly. "Is there?" said Anthony, puzzled, "but why----"