“I ought to. He showed it to me often enough. Red limp-leather cover—thin yellow pages—two or three clips on every sheet holding notations—his name gold-stamped in large letters on the binding. . . . Poor devil! Sic transit. . . .”

“Where would this note-book be now?”

“One of two places—either in the drawer of his desk in the study or else in the escritoire in his bedroom. In the daytime, of course, he worked in the study; but he fussed day and night when wrapped up in a problem. Kept an escritoire in his bedroom, where he put his current records when he retired, in case he got an inspiration to monkey with ’em during the night. Then, in the morning, back they’d go to the study. Regular machine for system.”

Vance had been gazing lazily out of the window as Arnesson rambled on. The impression he gave was that he had scarcely heard the description of Drukker’s habits; but presently he turned and fixed Arnesson with a languid look.

“I say,” he drawled; “would you mind toddling up-stairs and fetching Drukker’s note-book? Look in both the study and the bedroom.”

I thought I noticed an almost imperceptible hesitation on Arnesson’s part; but straightway he rose.

“Good idea. Too valuable a document to be left lying round.” And he strode from the room.

Markham began pacing the floor, and Heath revealed his uneasiness by puffing more energetically on his cigar. There was a tense atmosphere in the little drawing-room as we waited for Arnesson’s return. Each of us was in a state of expectancy, though just what we hoped for or feared would have been difficult to define.

In less than ten minutes Arnesson reappeared at the door. He shrugged his shoulders and held out empty hands.

“Gone!” he announced. “Looked in every likely place—couldn’t find it.” He threw himself into a chair and relighted his pipe. “Can’t understand it. . . . Perhaps he hid it.”