“Do you think it will, Mr. Vaux?”

“Maybe it will,” he said, not believing it.  He added:  “I think, however, your undoubted ability is going to land us both in jail.”

At which pessimistic prognosis they both began to laugh.  She was very lovely when she laughed.

“I hope they’ll give us the same cell,” she said.  “Don’t you?”

“Surely,” he replied gaily.

Once he remembered the photograph of Arethusa in his desk at headquarters, and thought that perhaps he might need it before the evening was over.

“Surely, surely,” he muttered to himself, “hum—­hum!”

Her coupe stopped in Fifty-sixth Street near Madison Avenue.

“The car will wait here,” remarked the girl, as Vaux helped her to descend.  “Lauffer’s shop is just around the corner.”  She took his arm to steady herself on the icy sidewalk.  He liked it.

In the bitter darkness there was not a soul to be seen on the street; no tramcars were approaching on Madison Avenue, although far up on the crest of Lenox Hill the receding lights of one were just vanishing.

“Do you see any policemen?” she asked in a low voice.

“Not one.  They’re all frozen to death, I suppose, as we will be in a few minutes.”

They turned into Madison Avenue past the Hotel Essex.  There was not a soul to be seen.  Even the silver-laced porter had retired from the freezing vestibule.  A few moments later Miss Erith paused before a shop on the ground floor of an old-fashioned brownstone residence which had been altered for business.

Over the shop-window was a sign:  “H.  Lauffer, Frames and Gilding.”  The curtains of the shop-windows were lowered.  No light burned inside.

Over Lauffer’s shop was the empty show-window of another shop—­on the second floor—­the sort of place that milliners and tea-shop keepers delight in—­but inside the blank show-window was pasted the sign “To Let.”

Above this shop were three floors, evidently apartments.  The windows were not lighted.

“Lauffer lives on the fourth floor,” said Miss Erith.  “Will you please give me the jimmy, Vaux?”

He fished it out of his overcoat pocket and looked uneasily up and down the deserted avenue while the girl stepped calmly into the open entryway.  There were two doors, a glass one opening on the stairs leading to the upper floors, and the shop door on the left.

She stooped over for a rapid survey, then with incredible swiftness jimmied the shop door.

The noise of the illegal operations awoke the icy and silent avenue with a loud, splitting crash!  The door swung gently inward.

“Quick!” she said.  And he followed her guiltily inside.

The shop was quite warm.  A stove in the rear room still emitted heat and a dull red light.  On the stove was a pot of glue, or some other substance used by gilders and frame makers.  Steam curled languidly from it; also a smell not quite as languid.