“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?”