“What do you want?” was the angry question of an indignant old caretaker who answered the bell tardily.  “You woke me up.”

“Say, lady, can I speak to Mr. Montague Shirley?” began the man, gingerly.

“You get away from this house, you loafer or I’ll call the police.  No one by that name ain’t here.  Now, you get!”

She slammed the door in his face.

“I’ll get Chuck to watch de udder joint,” muttered the man, in a tone audible to Shirley.  “Den I’ll go back and git orders from Phil.”

This habit of thinking aloud was expensive.  Shirley stiffly but noiselessly slid down the steps, as he disappeared in the thickening snowfall.  The criminologist slowly crossed the street, and sheltered himself in a basement entrance, from which he reversed the shadowing process.  The twain hesitated before the first house, then one came up the sidewalk, as the other stood his ground.  This man passed within a few feet of Shirley, who followed him over to Madison Avenue, then north to Fifty-fifth Street.  Here he turned west, and turned into one of the old stables, formerly used by the gentry of the exclusive section for their blooded steeds.  Into one building, which announced its identity as “Garage” with its glittering electric sign, the man disappeared.

Shirley paused, looked about him, and chuckled.  For he knew that through the block on Fifty-sixth Street was the tall apartment building, known as the Somerset—­the address given him by Reginald Warren.

“If I only had some word from Helene Marigold I could go ahead before they realized my knowledge.”

Even as this thought crossed his mind, he turned back into Sixth Avenue.  A hatless, breathless young person, running down the snowy street collided with him.  As he began to apologize, he awoke to the startling fact that it was his assistant.

“Great Scott!  What are you doing here?  Where have you been all this time?”

The girl caught his arm unsteadily, but there was a triumph in her voice, as she cried:  “Oh, this wonderful chance meeting.  I was running down to my hotel but you have saved the day.  I will tell you later.  Quick, take this book.”

She drew forth a volume, flexibly bound, like a small loose-leaf ledger.  Shirley stuck it into his overcoat pocket, which he was already slipping about the girl’s shivering shoulders.

“Take me back at once, for there is more for me to do.”

“Where, my dear girl?  You are indeed the lady of mysteries.”

“To the basement of Warren’s apartment house.  I came down the dumb-waiter, when they left me.  I left the little door ajar—­Can you pull me up again?  He is on the eighth floor.  It is a long pull—­Oh, if we can only make it before they return.”

Her eyes sparkled with the thrill of the mad game, as she ran once more, Shirley keeping pace with her.  The flurries of the snowstorm protected them from too-curious observation, as the streets seemed deserted by pedestrians who feared the growing blizzard.  She led him to the tradesman’s entrance of the Somerset, into the dark corridor through which she had emerged.