The lunchroom was practically empty, and in two chairs near him the proprietor and his assistant were sitting talking.  Aubrey was suddenly struck by what they said.

“Say, this here, now, bookseller guy must have struck it rich.”

“Who, Mifflin?”

“Yeh; did ya see that car in front of his place this morning?”

“No.”

“Believe me, some boat.”

“Musta hired it, hey?  Where’d he go at?”

“I didn’t see.  I just saw the bus standing front the door.”

“Say, did you see that swell dame he’s got clerking for him?”

“I sure did.  What’s he doing, taking her joy-riding?”

“Shouldn’t wonder.  I wouldn’t blame him——­”

Aubrey gave no sign of having heard, but got up and left the lunchroom.  Had the girl been kidnapped while he overslept?  He burned with shame to think what a pitiful failure his knight-errantry had been.  His first idea was to beard Weintraub and compel him to explain his connection with the bookshop.  His next thought was to call up Mr. Chapman 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.”