im.
For the note had been written in this very room, on stationery
conveniently at hand, on the noiseless typewriter which had been far
more considerate about not betraying the intruder than had the parrot
whose slumbers had been disturbed.

"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:

"Bad Penny! Bad Penny!"

"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