“I say, Chick,” said Patsy, “did you see how Lannigan came out of that house and how he looked to see if anybody was about?”

“Yes, I saw that,” said Chick. “He was suspicious.

“Of being followed?”

“Not of us, probably, but of anybody seeing where they go.”

The way of the four was now back in the direction of the more thickly settled part of the city.

Finally they reached a corner house, the lower part of which was a drinking place.

The house was a peculiar structure, entrance to the upper story being gained by a high stoop from the outside. Back of it was another building, separated from it by narrow iron bridges on every one of the four floors.

This rear building was not as wide as the one in front, so that there was a space of a few feet between that building and the cross street.

This space was concealed by a high board fence, which, to the two young detectives, looked more like the side of a house than a fence.

There were large double doors in this fence. But they were closed.