“Fine.  Those things the Chief can take care of.  That leaves the way clear for us to-morrow afternoon.”

“What excuse will I make for having you come up to the apartment?”

“You want me to change some pictures.  That will account for the wire if I’m caught.”

“I hope no one sees you.”

“Nobody’ll see me but the elevator man, and he’ll think nothing of it.”

Apparently, too, Dean was right, for the next afternoon he entered the Strong apartment carrying a suitcase in which was concealed his apparatus and the necessary wire.

“Hurry,” cried Jane, who was waiting for him.  “The Hoffs’ maid has just gone up on the roof.”

“We can safely give her at least a few minutes,” said Dean setting to work to make a hole through the wall into the apartment adjoining.  Just as he had finished making it and had pushed one end of the wire through, the telephone bell rang, and Jane in dismay sprang to answer it.

“Disguise your voice,” warned Dean.  “If it is a caller say there is no one home.”

“It was Lieutenant Kramer calling,” said Jane as she returned.

“Did he recognize your voice?”

“I don’t think so.”

“What did he say?”

“He said to tell Miss Strong that he had called.”

“Then he didn’t suspect you.”

“Isn’t there danger, though, that he may come up to the Hoff apartment?”

Dean sprang to the window and looked out at the street below.

“No, there he goes up the street.  He evidently did not try to see if the Hoffs were at home.  That’s funny.”

“Why funny?”

“It means of course that he, too, knows about those Wednesday trips the Hoffs make.”

Cautiously he opened the door into the public hall.  There was no one about.  Catlike in swiftness and silence he moved to the Hoff door and inserted his new-made key.  It worked perfectly.

“Now,” he whispered to Jane, “to the roof—­quick.  I must not be taken by surprise.  Give me at least ten minutes more—­fifteen if you can.”

Quickly he passed inside, closing the door behind him all but a barely noticeable crack, as Jane rang for the elevator and bade the operator take her to the roof.  As she emerged there and stood waiting for the elevator to descend again, an ornamental lattice screened her from the rest of the roof.  Cautiously and curiously she peered between the slats, trying to see what the Hoff servant was doing at the moment.  She decided that she would not reveal her presence until the woman made ready to go down-stairs.

As from behind her screen she scanned the roof she espied old Lena over on the side next the river bending over a half-filled basket of clothes, apparently putting into the basket some of the freshly dried laundry from the lines extending all over the roof.  As Jane watched her the old woman straightened herself up and cast a cautious glance about.  Apparently satisfied that she was alone she whipped out something from a pocket in her apron and turned in the direction of the river.