"I was aroused by the bell ringing," replied Hulme. "I am a very light sleeper. But I heard or saw nothing supernatural." "By the way, Hulme," said my friend, "the Turret Room is directly above the hall. I have a theory. Might I come up with you for a moment?" "Certainly," replied Hulme. We all went up to the Turret Room. Having climbed the stairs to this apartment, you enter it by descending three steps. It is octagonal and panelled all around. My friend tapped the panels and sounded all the oaken floor-boards. Then, professing himself satisfied, he bade Hulme good night, and accompanied me to my room. VI Ragstaff Park slumbered once more. But Lorian sat upon the edge of my bed, smoking and thinking hard. He had been to his own room for the print of the Riddle, and it lay upon a chair before him. "Listen to this," he said suddenly: "(_a_) Some one breaks into the governor's studio, and takes nothing. His drawings of the Ragstaff Riddle happen to be at my studio. (_b_) You hear a noise in the night, and see (1) a bright light; (2) a gleaming rod. (_c_) You and I see a bright light on the following night, and presumably proceeding from the same place; i.e., the hall. (_d_) Something I have not mentioned before--Hulme has a camera in his kit! And he doesn't want the fact known!" "What do you mean?" "I tested him the other night, by inquiring if anyone could lend me a camera. He did not volunteer! The morning following the mysterious business in the hall, observed by you, I saw a photographic printing frame in his window! He must have one of those portable developers with him." "And to what does all this point?" "To the fact that he has made at least three attempts to obtain a copy of the Riddle, and has at last succeeded!" "Three!" "I really think so. The evidence points to him as the person who broke into the studio. He made a bad slip. He referred to the matter, and cited Horace Baxter as his informant. Baxter is away!" "But this is serious!" "I should say so! He couldn't attempt to photograph the panel in daylight, so he employed magnesium ribbon at night! First time his tripod slipped. It is evidently one of the light, telescopic kind. His negative proved useless. It was one of the metal legs of the tripod which you saw shining! The second time he was more successful. That was the light of his magnesium ribbon you and I saw from the drive!" "But, Lorian, I went down and searched the hall!" "Now we come on to the, at present, conjectural part," explained Lorian. "My theory is that Hulme, somewhere or other, has come across some old documents which give the clue to those secret passages said to exist in Ragstaff, but which the Colonel has never been able to locate. I feel assured that there is some means of secret communication between the Turret Room and the hall. I further believe that Hulme has in some way got upon the track of another secret--that of the Riddle." "But what _is_ the secret of the Riddle?"