"Why, yes," she exclaimed. "Just before I went to Canada, and Mr. Zybinn developed the negatives for me. He was a paralytic, and while unable to walk, dabbled in photography. He had some enlargements made of my kodak films." "And one of this room?" quickly. "Yes. He said it was a remarkably good interior and made me describe all the objects in it--" "Especially this"--going over to the wall, Trenholm took down a picture and held it in plain view. He stopped as the constable and Riley came into the bedroom, the latter with a sheaf of telegrams in his hand. "Ah, Constable, you are just in time--this picture was made by Paul's mother, who was an artist of some ability. She modeled it after those quaint Swiss paintings of a cemetery with a church in the background, in which a _real_ clock was put in the tower. In this picture of the Masons' neglected burying ground, Mrs. Abbott etched in the background a church tower and _placed in the tower this antique watch_." Trenholm turned the picture around and pointed to a watch, a tiny affair, which was firmly held in the canvas by a clever contrivance. He drew out the watch with a careful hand, the others watching him breathlessly. "The first word of the code is 'watch.' Here it is," Trenholm held up the antique watch. "The next two words, 'thirteenth letter,' which is 'M', you will find is the initial engraved on the back of the watch; and the last two words, 'suicide's grave,' exemplified by this picture of Colonel Mason's grave." Trenholm turned to Betty and asked: "Did you not tell Zybinn that you chanced to see Paul remove the works from this watch?" "Yes," she admitted. "Zybinn asked me if the watch was too old to keep accurate time and I told him Paul had taken it apart." "So that was it," and Trenholm nodded. "Paul removed the works from the watch because he evidently judged it to be an admirable hiding place for--" "The Paltoff diamond!" shouted Roberts. For answer Trenholm opened the watch. Inside the round hollow lay a wad of cotton--and on top of it the lost jewel. They gathered about the table, even Roberts, forgetful for a brief second that he was handcuffed, and gazed at the beautiful gem, dazzled by its luster and purity. Trenholm was the first to speak. "Paul knew little rest after the Paltoff diamond was intrusted to his care. He was constantly haunted by a morbid fear of losing it or of being robbed of it, so that he could never be induced to exhibit it."