It was very dark, and at first he could see nothing.
Finally, however, he heard a noise on the roof of the next building, which was several feet lower than the roof of the one upon which the detective then stood.
He crept to the edge and looked down.
A figure stood on the wall at the rear, looking over an alley, at least twelve feet wide.
As the detective looked, the figure sprang into the air and landed on the other side.
It was a desperate act, but well carried out.
“Gilmore still has his old nerve,” thought Nick. “I wonder if I could jump that alley?”
He could, and he did, but when he stood in safety on the other side, Gilmore had disappeared.
Nick prowled around on the roof a long time, and was about to take his departure when a low cry of fright reached his ears.
He crept softly in the direction from which the sound had proceeded, and found a faint light shining through a skylight in the roof.