"But why did my unknown friend risk arrest as a burglar if he wanted to give me an honest tip?" Dundee remarked aloud to the parrot, who croaked an irrelevant answer:
"I'm afraid, 'my dear Watson,' that those words will not be so helpful in this case as they were when your mistress was murdered," Dundee assured his parrot absently, for he was studying the peculiar situation from every angle. "Another question, Cap'n--why did the unknown bother to take my 'Who's Who' out of the bookcase, where I should normally have looked for it, and put it on that particular shelf?"
Warily, for his scalp was prickling with a premonition of danger, Dundee crossed the room to the shelf, but his hand did not reach out for the red book, which might have been expected to solve one problem, at least. "_Why the shelf?_" he asked himself again. Why not the desk top, or the mantelpiece, or the smoking table beside the big armchair?
The shelf, with its drapery of rather fine old silk tapestry, offered no answer in itself, for it held nothing except the red book, a Chinese bowl, and a humidor of tobacco. And beneath the shelf was nothing but the old-fashioned register, the opening covered with a screwed-on metal screen which was a mass of big holes to permit the escape of hot air when the furnace was going in the winter....
Suddenly Dundee stooped and stared with eyes that were widened with excitement and a certain amount of horror. Then he rose, and, standing far to one side, picked up the fat volume which lay on the shelf. As he had expected, a bullet whizzed noiselessly across the room and buried itself in the plaster of the wall opposite--a bullet which would have ploughed through his own heart if he had obeyed his first impulse and gone directly to the shelf to obey the instructions in the note.
But more had happened than the whizzing flight of a bullet through one of the holes of the hot-air register. The "Who's Who" had been jerked almost out of Dundee's hand before he had lifted the heavy volume many inches from the shelf. Coincidental with the disappearance of a bit of white string which had been pinned to a thin page of the book was a metallic clatter, followed swiftly by the faint sound of a bump far below.