man and warn him of what had been going on. Then he decided it
would be futile to do either of these before he really knew what had
happened. He determined to get into the bookshop itself, and burst
open its sinister secret.

He walked hurriedly round to the rear alley, and surveyed the domestic
apartments of the shop. Two windows in the second storey stood
slightly open, but he could discern no signs of life. The back gate
was still unlocked, and he walked boldly into the yard.

The little enclosure was serene in the pale winter sunlight. Along one
fence ran a line of bushes and perennials, their roots wrapped in
straw. The grass plot was lumpy, the sod withered to a tawny yellow
and granulated with a sprinkle of frost. Below the kitchen door--which
stood at the head of a flight of steps--was a little grape arbour with
a rustic bench where Roger used to smoke his pipe on summer evenings.
At the back of this arbour was the cellar door. Aubrey tried it, and
found it locked.

He was in no mood to stick at trifles. He was determined to unriddle
the mystery of the bookshop. At the right of the door was a low
window, level with the brick pavement. Through the dusty pane he could
see it was fastened only by a hook on the inside. He thrust his heel
through the pane. As the glass tinkled onto the cellar floor he heard
a low growl. He unhooked the catch, lifted the frame of the broken
window, and looked in. There was Bock, with head quizzically tilted,
uttering a rumbling guttural vibration that seemed to proceed
automatically from his interior.

Aubrey was a little dashed, but he said cheerily "Hullo, Bock! Good
old man! Well, well, nice old fellow!" To his surprise, Bock
recognized him as a friend and wagged his tail slightly, but still
continued to growl.

"I wish dogs weren't such sticklers for form," thought Aubrey. "Now if
I went in by the front door, Bock wouldn't say anything. It's just
because he sees me coming in this way that he's annoyed. Well, I'll
have to take a chance."

He thrust his legs in through the window, carefully holding up the sash
with its jagged triangles of glass. It will never be known how
severely Bock was tempted by the extremities thus exposed to him, but
he was an old dog and his martial instincts had been undermined by
years of kindness. Moreover, he remembered Aubrey perfectly well, and
the smell of his trousers did not seem at all hostile. So he contented
himsel