HE first point of destination of the police squad, was to the door out of which Will had made his escape, and he led the men directly to it. It was unlocked, as he had left it, but four men were left there, and the others followed the boy around to another street, where was the number at which he had entered the den.

"I've made no mistake in this number, but yet it don't look like the place," he said as he stopped before the door.

"I hope you have made no mistake, my lad," anxiously said Captain Daly.

"I know I have not, sir; but then I can't find the bell."

In vain he searched, there was no bell at the side, but instead a large old-fashioned knocker.

"This is a white door, sir, as you see, and the other was painted brown."

"Then you are certainly mistaken, my lad."

"No, sir, I am not mistaken, for this is the number, but—"

"But what?" asked Captain Daly, as Will paused.

"They have taken out the bell from the side, sir, and changed the door, since I left."

Several of the policemen laughed, but Captain Daly did not, and said: "If you say so, Will, I'll believe you.

"Your dark lantern here, Gibson."

The man addressed handed over his lantern, and Will ran the light up and down the door-post.

"Here's where the bell-knob was, sir, and it's been plugged up as you see, by something that fits in."

"You are right, Will," and the captain gave the knocker three sharp blows.

But no response came, and Will said: "They'll not answer, sir, for they've changed this door to fool me, and they know I've escaped from that man I locked in his room."

"All right, we'll open the door ourselves.

"In with it, men!"

Half a dozen policemen threw themselves against the door; but it withstood their weight, and the locks within only yielded after repeated trials. Then the door flew open, and all entered the hallway, closing it behind them.

The next door then confronted them, but Will pointed out the panel, and a club smashed that in, when Captain Daly put in his hand and drew back the bolt.

"This is a secure nest, that is certain; but I fear we'll find it deserted," said Captain Daly, and with their lantern-shades raised, they hastily followed Will up the stairs.

He went directly to the door by which he had entered, and the panel was opened with a club, and the officers dashed in, and throwing themselves against the inner door it yielded to their weight with a crash.

Then they found themselves in the large living room of the band, from whence Will had made his escape.

The bunks were there, the table, chairs, dumb-waiter, and much clothing and bedding was scattered about, showing a hasty departure; but not a soul was present.

"Will you follow down the chimney, sir?" asked Will.

"Yes, I will follow with several of my men, while the remainder break in every door of this nest, which is, indeed, a safe retreat.

"Come, men, I want only those who have cool heads on lofty places to go, for, from what he told me, it will require all your nerve to follow him."

Four of the officers volunteered, and up the ladder went Will, he having in the meantime recovered his hat, shoes and jacket from the floor.

Out upon the roof, in the drenching rain, the boy stepped, and made his way fearlessly along the dizzy hight, followed by Captain Daly and his men, who stepped with the greatest caution, for they realised their deadly peril at a glance.

Fearlessly the brave boy led the police captain and his men, the chief calling out: "Go slow, Will, for a false step here will send us to perdition!"

Reaching the chimney, Will sprang upon the top and disappeared in the interior, the others following, and descending the iron ladder in silence.

Down to the fire-place went Will, and the instant after Captain Daly joined him, and handing the boy his dark-lantern to spring open, the two hastily sprang out into the room.

It was deserted, but the door was partly open, for the lock had been wrenched off.

The pictures were on the wall, the bed all rumpled up, and the lamp was upon the table, while there was every indication of a hasty departure, as in the assembly room.

Then the police went on a voyage of discovery through the house.

It was an old-time mansion, two stories, narrow in build, and ran back against the one on the other street, to which the false chimney belonged, and in it were some half-score of poor, but reputable lodgers, who, aroused by the police, were amazed at the raid upon them.

In answer to inquiries, they said that the room on the rear, through which the officers had come, was occupied by an artist, they had heard, though no one seemed to know much about him except that he had a number of visitors.

That there was a secret connected with his living there they had not suspected.

Confident that the lodgers of the house told the truth, Captain Daly left two of his men on duty there, and started around the block to the other house.

He found the party still on guard at the door, and they had not seen or heard anything of a suspicious nature.

Going around to the other house Captain Daly found that his men had thoroughly searched the place from the cellar to the attic.

They had discovered the door which Will had remembered to have seen in front, and as it was still dripping wet it showed that it had been removed that night from its place, to throw the boy off his guard, but it had, however, failed to do so.

In different rooms of the house was found a quantity of stolen booty, the loss of some of which Captain Daly and his men had heard of, and there was every indication that it was a nest of burglars of a daring and desperate nature.

The Land Sharks had long been known to the police for their bold acts of crime, yet they never before could be located, and even the gruffest of the policemen praised Will for what he had done.

Dawn was now breaking, and a neighbour, coming out of his house, was asked who owned the premises.

He said that his landlord did so, and giving the address, the proprietor of the two houses was at once looked up; but he was amazed at what he heard, for he let the property to an old woman who said she wished to keep boarders, and had regularly paid her rent three months in advance, and had built a new chimney and made other improvements which she had paid for herself.

The landlord was greatly amazed to find what those improvements were, but he could give no clue as to who or what his tenant was, or where she could be found.

Having discovered the secret retreat of the Land Sharks, however, was a cause of congratulation, and the booty found was considerable, so that Will was praised for his good services, and at once told that he was to consider himself a member of the Secret Service and to report the following day after he had become rested, for the night of peril and hardship the good-hearted police-captain could see had told on the brave boy.

With a heart bounding with joy, Will had hastened home, and his mother and sister greeted him warmly, for they were most anxious regarding his long absence, and with wonder they listened to the strange story of his adventures, while Pearl cried in glee: "Hurrah for the Boy Detective!"