Once the man turned and gazed at the two figures behind him; then, apparently satisfied that he was not being followed, he moved on again.

After two more blocks he doubled around a corner.  Frank and Jack turned the corner a moment later, just in time to see Davis mount a short flight of steps, open a door and enter the house.

Frank and Jack walked by, taking careful note of the number of the house, however, and without glancing up again, continued down the street and turned the next corner.

There they halted as of one mind while Frank peeped around the corner, remarking: 

“Don’t want him to trick us.  I don’t think he knew he was being followed, but you never can tell.”

The lads stood there for perhaps ten minutes; then Jack reached a decision.

“As long as we have come this far,” he said, “we may as well finish this man hunt.  We’ll go and have a look for him.”

“How do you figure we are going to get into the house?” demanded Frank.  “Or do you just plan to ring the bell and ask for ’Mr. Davis’?”

“We’ll have to get in some way,” returned Jack, “or else admit that we are wrong.”

“I won’t admit I’m wrong,” declared Frank grimly.  “I feel positive the man is Davis.”

“So do I,” replied Jack; “else I wouldn’t be so keen about getting into that house.  We’ll go back and skirmish around a bit, anyhow.”

They retraced their steps slowly, and passing the house where the man had entered, took careful note of it.

It was a two-story building.  Steps led to a porch, not high above the street, but still high enough to make the single window in front beyond reach from the street below.  A narrow passage was between it and the house on the left.  It was built flush against the house on the right.

At the corner the lads again turned and retraced their steps.  “I’m going to try the door,” said Jack.  “You slink back in that dark alleyway until you hear from me.”

Frank signified that he understood, and passing the house, did as Jack had instructed, the latter mounting the steps quietly and swiftly.

The lad laid a hand on the knob and turned it.  Then he pushed on the door, but it held fast.

“Locked,” he said, plainly disappointed.

There was no window in the little vestibule and the single front window was beyond reach from the porch.  Neither was there a transom that could be forced.

“No means of getting in here,” Jack told himself.

He descended the steps and joined Frank in the alleyway.

“Well?” Frank greeted him.

Jack shook his head.

“Can’t get in that way,” he said.

“Well,” said Frank, “I have been doing a little exploring while you were up there and I have found a way.”

“How?” asked Jack, a little surprised.

For answer, Frank motioned to a little aperture in the side of the house, close to the ground.