fought with you?"

"Fearful! Yo' see, he had worked his hands free from de bonds. Done gib
me a strong tussle when I was a-gwine ter take him into--into----"

"What?"

"His prison, sah."

"If you don't tell where it is, we shall shoot you, sir!"

As Old King Brady made this threat he pushed his revolver against
Nick's forehead, and the coon gave a wild yell of terror.

"Fo' hebbin's sake," he groaned, "doan fire!"

"I'll solve the mystery of this swamp, or I'll murder you!" fiercely
cried the old detective. "Do you hear me, sir?"

A cold sweat burst out all over the darky.

He gazed around in alarm, and gasped hoarsely:

"If I tell, will yo' gib me away?"

"To whom?"

"Massa Mason."

"Of course not."

"Den listen. Dar's a tunnel under de flo' ob dat hut."

"Where does it lead to?"

"A big cave under de island in de swamp."

"How do you reach it?"

"Froo a trap-doo' in one corner, covered wid earf."

"And that's where Mason is keeping his prisoner, eh?"

"Yassah. We free lib dar."

"Is that where you carried Dalton on the night you took him from the
cars?" demanded Old King Brady.

"Ob co'se," replied the coon. "An' if Mason find out dat I done tell
yo' about it, 'spect he'd kill me like a dog."

"No doubt he would," said the old detective. "He is capable of doing
almost any kind of villainy. Where were you to-night?"

"Bringin' food fo' de cave, as our supply ran out."

"I thought as much."

Just then Harry muttered:

"Well, the great swamp mystery turns out to be a very simple matter,
now that we fully understand it, Old King Brady."

"This man may be lying, Harry."

"We can easily prove what he has told us."

"Yes, indeed. And if we find Mr. Dalton kept a prisoner it will go
mighty hard with Mason when we capture him. I'm glad to hear that the
old broker had the nerve to resist his demands, for it looks to me as
if his nephew were trying to amass all the money he can get his hands
on in order to escape from here as soon as possible."

They questioned Nick for a while longer.

Then they brought him to the town, and had him locked up.

Returning to the Dalton mansion, and meeting Lizzie, they told her what
they discovered by pumping the negro.

She was, of course, delighted to learn that her father was alive, and
was eager for the detectives to go to his rescue.

"We'll make the attempt to-morrow morning," said Harry.

"I don't see why you are putting it off so long," excl