ALLAN could scarcely believe his eyes. The detective certainly ran into the alley, and there seemed to be no escape from the alley save by the flight of wooden steps running up the side of the building on the left. These steps were in full view to the top, and it certainly was impossible that Dobbs should have mounted these in the brief moments that had elapsed before Allan reached the point from which he could see them.

For several minutes Allan stood there in perplexity. Then he walked as far as the corner and back again to the alley. Still no sign of Dobbs. A Chinaman in a tea-shop came to the door and stared at Allan. Other Chinamen across the way seemed to be wondering what he wanted there. Two barefooted Italian boys stopped, and very deliberately examined the camera and Allan.

Allan again walked to the corner, and as he turned he saw a little ragged boy enter the alley, and he lost no time in retracing his steps. But when he reached the alley the boy was not to be seen. He, too, had melted away.

Allan then determined to settle this mystery if he did nothing else, and to wait there until another figure attempted to elude him. “I’ll follow them,” he said to himself.

The Chinaman in the tea-shop saw Allan take his stand at the curb opposite the alley. For five minutes or more he stood there watching the life of the street, peering at the strange signs and banners and balconies. He looked toward Chatham Square, from which came the clatter of the elevated trains and the roar of street traffic. Occasionally he turned to the alley as if expecting to see Dobbs reappear from its shadowy depths.

Once, when his eyes turned to the alley, he saw a man with a red shirt shambling toward him, a lame man who leaned against the sides of the alley to support himself. But it was impossible to see where he had come from. The mystery was as deep as ever—as deep as the alley.

Presently a woman who passed him with a bundle of clothes entered the alley with a rolling step, and Allan instantly followed her, to the evident perplexity of the Chinaman in the tea-shop. He followed so closely at the woman’s heels in his determination not to let her melt out of his sight, that the woman glanced back at him over her shoulder in suspicious inquiry.

Then Allan discovered what many another discovered long ago, for when the woman reached what had appeared to be the end of the alley, she turned to the right, and the boy, following, found himself in another alley running at right angles to the first.

It seemed very absurd that he had not thought of this before. Several doors opened into this second alley, and through one of these the woman passed with her bundle.