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.
Vaux handed her an electric torch, then flashed his own. The next moment she found a push button and switched on the lights in the shop. Then they extinguished their torches.
Stacks of frames in raw wood, frames in "compo," samples gilded and in natural finish littered the untidy place. A few process "mezzotints" hung on the walls. There was a counter on which lay twine, shears and wrapping paper, and a copy of the most recent telephone directory. It was the only book in sight, and Miss Erith opened it and spread her copy of the cipher-letter beside it. Then she began to turn the pages according to the numbers written in her copy of the cipher letter.
Meanwhile, Vaux was prowling. There were no books in the rear room; of this he was presently assured. He came back into the front shop and began to rummage. A few trade catalogues rewarded him and he solemnly laid them on the counter.
"The telephone directory is NOT the key," said Miss Erith, pushing it aside. A few moments were sufficient to convince them that the key did not lie within any of the trade catalogues either.
"Have you searched very carefully?" she asked.
"There's not another book in the bally shop."
"Well, then, Lauffer must have it in his apartment upstairs."
"Which apartment is it?"
"The fourth floor. His name is under a bell on a brass plate in the entry. I noticed it when I came in." She turned off the electric light; they went to the door, reconnoitred cautiously, saw nobody on the avenue. However, a tramcar was passing, and they waited; then Vaux flashed his torch on the bell-plate.
Under the bell marked "Fourth Floor" was engraved Herman Lauffer's name.
"You know," remonstrated Vaux, "we have no warrant for this sort of thing, and it means serious trouble if we're caught."
"I know it. But what other way is there?" she inquired naively. "You allowed me only twenty-four hours, and I WON'T back out!"
"What procedure do you propose now?" he asked, grimly amused, and beginning to feel rather reckless himself, and enjoying the feeling. "What do you wish to do?" he repeated. "I'm game."
"I have an automatic pistol," she remarked seriously, tapping her fur-coat pocket, "—and a pair of handcuffs—the sort that open and lock when you strike a man on the wrist with them. You know the kind?"
"Surely. You mean to commit assault and robbery in the first degree upon the body of the aforesaid Herman?"
"I-is that it?" she faltered.
"It is."
She hesitated:
"That is rather dreadful, isn't it?"
"Somewhat. It involves almost anything short of life imprisonment.
But I don't mind."
"We couldn't get a search-warrant, could we?"
"We have found nothing, so far, in that cipher letter to encourage us in applying for any such warrant," he said cruelly.
"Wouldn't the excuse that Lauffer is an enemy alien and not registered aid us in securing a warrant?" she insisted.
"He is not an alien. I investigated that after you left this afternoon. His parents were German but he was born in Chicago. However, he is a Hun, all right—I don't doubt that…. What do you propose to do now?"
She looked at him appealingly:
"Won't you allow me more than twenty-four hours?"
"I'm sorry."
"Why won't you?"
"Because I can't dawdle over this affair."
The girl smiled at him in her attractive, resolute way:
"Unless we find that book we can't decipher this letter. The letter comes from Mexico,—from that German-infested Republic. It is written to a man of German parentage and it is written in cipher. The names of Luxburg, Caillaux, Bolo, Bernstorff are still fresh in our minds. Every day brings us word of some new attempt at sabotage in the United States. Isn't there ANY way, Mr. Vaux, for us to secure the key to this cipher letter?"
"Not unless we go up and knock this man Lauffer on the head. Do you want to try it?"
"Couldn't we knock rather gently on his head?"
Vaux stifled a laugh. The girl was so pretty, the risk so tremendous, the entire proceeding so utterly outrageous that a delightful sense of exhilaration possessed him.
"Where's that gun?" he said.
She drew it out and handed it to him.
"Is it loaded?"
"Yes."
"Where are the handcuffs?"
She fished out the nickel-plated bracelets and he pocketed his torch. A pleasant thrill passed through the rather ethereal anatomy of Mr. Vaux.
"All right," he said briskly. "Here's hoping for adjoining cells!"
To jimmy the glass door was the swiftly cautious work of a moment or two. Then the dark stairs rose in front of them and Vaux took the lead. It was as cold as the pole in there, but Vaux's blood was racing now. And alas! the photograph of Arethusa was in his desk at the office!
On the third floor he flashed his torch through an empty corridor and played it smartly over every closed door. On the fourth floor he took his torch in his left hand, his pistol in his right.
"The door to the apartment is open!" she whispered.
It was. A lamp on a table inside was still burning. They had a glimpse of a cheap carpet on the floor, cheap and gaudy furniture. Vaux extinguished and pocketed his torch, then, pistol lifted, he stepped noiselessly into the front room.
It seemed to be a sort of sitting-room, and was in disorder; cushions from a lounge lay about the floor; several books were scattered near them; an upholstered chair had been ripped open and disembowelled, and its excelsior stuffing strewn broadcast.
"This place looks as though it had been robbed!" whispered Vaux.
"What the deuce do you suppose has happened?"
They