"I won't. See all the harm you've done me. In the first place, you've cheated me out of a fortune. In the second place, you prevented me from getting the girl I loved. In short, you've baffled me at every turn, after I made the most elaborate preparations to succeed."

"We did our duty."

"Oh, that be hanged! You'd kill me to do your duty, and I'm justified in ridding myself of such enemies as you two are."

"If you hadn't done wrong you would not have had us after you."

"Well, I know that very well. It's stale news. But I had an object in what I did, and you interfered and foiled me. I didn't do any one much harm, and – "

"You robbed Oliver Dalton and put him out of the way."

"Robbed him?"

"Yes. You pilfered money from the mail."

"How do you know I did?" asked Mason, with a startled look.

"Dalton employed us to expose you, and we'd been at his house on the night you and Johnson were posing in Thirty-sixth street as undertakers."

"The deuce! I didn't know Dalton knew."

"You admit, then, that you did rob his mail?"

"No use denying it now," laughed Mason. "I freely admit that I did get away with thousands of his dollars in that way. No use trying to conceal it. You'll never get out of there alive to prosecute me. And even if you do, you've got enough other evidence against me to send me up as high as a kite."

Despite his peril Old King Brady felt triumphant.

They now knew who the mail thief was.

By this time the Bradys were sunk in the quick-sand to their hips, and were unable to move in any direction.

They kept sinking every moment with horrible rapidity.

"Well, we can't arrest you now for that crime," said Old King Brady, "but I've got a feeling that we shall do so yet."

"Humbug! You are getting dopy. You can't escape from there."

"Are you going to abandon us to our fate?"

"Yes; I wish you a merry voyage over the River Styx!"

And with a mocking bow and a jeering laugh, he strode away.

The Bradys began to shout for help again, and Mason paused, and, darting an angry look at them, he shouted threateningly:

"If you don't shut up we'll shoot you!"

"So much the better," replied Old King Brady. "It will end our misery."

"Oh, we won't shoot to kill," growled the scowling rascal, "but we will riddle your carcasses with painful wounds."

"Mason, you're a fiend."

"Am I? That's a compliment."

And with a short laugh he disappeared in the bushes.

Once more the detectives began to call for assistance, for they now were sunk to their armpits in the sand.

Their voices sounded hoarse and smothered, and a despairing feeling was creeping into their hearts, but they kept on shouting.

Presently Mason shouted at them from the bushes in angry tones:

"Are you going to shut up?"

"No!" roared Old King Brady.

"Then I'll pepper you!"

And bang! went his rifle, and a bullet whistled by their heads.

"Keep on yelling, Harry!" gasped the old detective.

"Help! Help!" shouted the boy, obediently.

Bang! went Mason's rifle again.

The ball grazed Harry's cheek, and stung like a bee.

Just then the shots and yells were heard by an old track-walker of the railroad, and he rushed around the swamp shouting:

"All right! I'm coming!"

This unwelcome voice to Mason caused a look of alarm to flit over his pale features, and, fearing arrest, he sped away.

The villain calculated that the detectives would be buried out of sight long before assistance could reach them.

But the Bradys were cheered up wonderfully.

They kept on shouting, and the track-walker finally found them by being guided by the tones of their voices.

Only their heads stuck above the water.

He stared at the pair in astonishment a moment, and cried:

"What in thunder are you doing in there?"

"Buried in quick-sand!" gasped Harry. "Help us – quick!"

The old fellow was startled and rushed in among the trees.

For a minute the detectives thought he deserted them. But he soon reappeared with a sapling he had cut with his pocket-knife.

Standing on the embankment, he reached out the end to Old King Brady, who lifted his hands above the water and grasped it.

"Pull!" gasped the detective.

The track-walker used all his strength, for the sand clung to the old detective tenaciously, and dragged him up.

Around him the sand stirred up and the water bubbled and eddied as it rushed into the opening left by his body.

After a fearful struggle Old King Brady was dragged free of the sand, and drawn to the shore, panting and drenched.

Harry had sunk to his chin.

It was only by keeping his head thrown back that he kept his mouth above water, and his two hands were raised.

Quick to act, and paying no heed to his own exhaustion, Old King Brady grasped the pole and thrust it out to the boy.

Half gone, Harry took hold.

Between the old detective and the track-walker he was hauled up and pulled ashore in a half-fainting condition. It was some time ere he revived.

But when his faculties returned, and the old track-walker had been thanked, the boy told their benefactor all that had happened.

He was surprised and indignant.

"That man Mason is a devil!" he exclaimed.

"We'll make short work of him for this terrible deed," said Harry.

"And I wish I could help you."

Shortly afterward the track-walker departed to resume his lonely tramp along the road-bed with a sledge over his shoulder to replace any spike or frogs dislodged by the passing cars.

Left alone, the Bradys glanced at each other, and Harry remarked softly:

"Our time hasn't come to perish yet, partner."

"I felt sure of that, even before that man came to our rescue."

"We've found out now what a desperate man Mason is."

"And we'll have to resort to drastic measures to get the best of him."

"How do you feel?"

"In a good humor to fight."

"Then let's go up to the house and tackle him."

"He will be surprised to see us alive."

They were thoroughly rested now, and, having examined their pistols and found them in working order, they proceeded up the hill.

Within a short time they reached the house, and rang the front door bell for admittance.

George Scott, the big negro whom they had met at the gate when they were there before, opened the door and grinned at them.

"Hello, George!" said Harry. "How are you?"

"Right smart, sah, thank you," chuckled the darky.

"Is Mr. Mason in?"

"Good Lawdy, no," replied the colored man. "An' de blame rascal better not come in dis yere house, or I'll blow de roof ob his head off, sho's yo's bo'n. I done know all he's been a-doin', I does."

"Why, who gave you the news?" asked Harry, in surprise.

"Missy Lizzie, sah. She arrive heah ter-day, bress her heart, an' she seen yo' a-comin', an' done tell me fo' ter ask yo' right inter de parlor. She be downstairs in a moment, Massa Brady. Come right in, gemmen, come right in."

And he led the detectives into the parlor, flung open the blinds, and left the room.

In a few moments the door opened and Lizzie Dalton stepped into the room and approached them, with a smile and extended hand.

CHAPTER XIII.
NICK WIFFLES EXPLAINS A MYSTERY

"So you found Ronald Mason prowling around the swamp, after you traced Sim Johnson down here from New York?" asked the broker's daughter, after the first salutations were over, and all were seated.

"We were under the impression that he had been making this house his abode," replied Old King Brady, in some surprise.

"No, indeed. George, the caretaker, declares that nobody but he and his wife have been in this house since you two gentlemen were here last."

"That is very strange," said the old detective.

"Why do you think so?" asked the girl, curiously.

"It puzzles me to account for Mason haunting the swamp and never coming near this house. Why is he hanging around that dismal swamp? What is the attraction that keeps him there with no friends or companions but those two negroes?"

"Was the other masked man a negro?"

"Yes. I saw the rascal's black skin plainly."

"Perhaps he is in the swamp to avoid arrest."

"No, no. He would not select such a malarious hole when there are so many pleasanter places for him to abide in. There is a deeper reason behind it. We must find out what it is."

"When he learns I am here, Mr. Brady, he may take it into his head to continue his persecutions."

"Not while we are here to protect you."

"Then you will be my guests?" eagerly asked the girl.

"Nothing would afford us greater pleasure."

"That makes my mind feel much easier."

"If your father should yet be alive and they should have him concealed somewhere around this swamp, it might account for their presence here."

"Yes, yes," she assented, eagerly. "You've proven conclusively that my poor father was not the man found in the river."

"In view of the fact that the game is up, so far as Mason is concerned, I can't fathom any object he may have in keeping your father a prisoner any longer. That is, of course, presuming he really has your father alive and imprisoned anywhere."

"Well," said the girl, reflectively, "I cannot give an opinion on that point at all. I can only keep on hoping that you may soon find my father, dead or alive. It would end this dreadful suspense and uncertainty about his fate."

At this juncture George's wife stuck her kinky head in at the door and announced that dinner was awaiting them.

The Bradys were shown to their rooms.

Having washed and made their toilets as best they could, they went down and joined Lizzie in the dining-room.

After that, several days and nights of hard work ensued.

The Bradys abandoned their disguises, merely wearing their top boots, and thoroughly scoured the swamp.

Not a trace of Mason or his two negroes was found.

It nettled the detectives, and finally drove them to the conclusion that the rascally trio had gone away.

Assured of this, the Bradys searched Swamp Angel.

No one there had seen anything of the men in question.

It therefore seemed quite evident that they cleared out of that neighborhood entirely, and assured of this, the Bradys started for home afoot that night.

"We shall have to leave here to-morrow," said the old sleuth, "and get upon their track elsewhere, Harry."

"It's a question how to find their trail," the boy answered, dubiously.

"As they more than likely went by rail, we could easily make inquiries of the passing train crews for some tidings of them."

Just then the pounding of horses' hoofs upon the road reached their ears, and they rushed behind a heap of rocks.

Parting some bushes growing there, they peered out.

The moon was rising in the cloudy sky, lighting up the dusty road, and the detectives caught view of two men on horseback.

They were coming from the direction of Pine Creek, the next railroad station beyond Swamp Angel, and carried bundles of provisions.

As Harry's glance fell upon the pair, he grasped Old King Brady's arm, and muttered in low, excited tones:

"It's Mason and Johnson, or some other negro."

"Hush! Keep quiet!" muttered Old King Brady.

Up came the horsemen, blissfully ignorant of the fact that the detectives were watching them, and Mason was laughing and saying:

"The fools were searching the swamp for us during the past three days, Nick, and they couldn't find a sign of us."

"Ha, ha, ha," laughed the negro. "'Specs dey am not so smart as dey fink dey am. An' what's mo', dey nebber find us."

Just then the detectives sprang from their covert.

Landing in the road in front of the two startled men, they grasped the horses' bridles at the bits, and the frightened beasts paused and reared up.

"Whoa!" yelled Mason. "What's that? Whoa!"

Old King Brady aimed a pistol up in his face.

"It's me!" he cried.

"Thunder!" roared the man.

"You throw your hands up."

"What for?"

"Because we want you!"

A sneering laugh pealed from Mason's lips.

He dug spurs into his horse's flanks, and the brute sprang forward, maddened with pain, and knocked the old detective down.

Over him bounded the horse, and the next moment it went galloping away into the woods a few yards ahead, and vanished.

Harry had been more fortunate.

As soon as he stopped the negro's horse, the black man raised a stick he carried and aimed a blow at the boy's head.

"G'way f'om dar!" he yelled.

Harry bounded out of reach of the blow.

The descending stick hit the horse and it gave a sudden leap that dismounted the man, and went plunging away at a furious rate.

The negro landed on his back on the ground.

In a moment Harry pounced upon him.

Pushing his pistol in the man's face, he cried:

"Surrender, you black fiend, or I'll bore you!"

"Don't shoot, boss!" roared the coon, frantically.

"Are you going to submit?"

"Yassah, yassah!"

"Without a fight?"

"Fo' sho' I is."

"Roll over on your face."

"Ober I go! Don't fire!" said the coon, turning over.

"Now, put your hands on your back."

"Heah dey am, boss!"

And the negro did as he was told.

Out came Harry's handcuffs, "click!" they snapped on his wrists, and in another instant the man was a prisoner.

When Old King Brady reached the boy he was pulling a big navy revolver out of the man's hip pocket.

"Got him, Harry?"

"Safe, Old King Brady."

"Get him upon his feet."

They raised the man, and now got a good square look at him.

He was a short, heavily-built fellow, clad in rags, and had as villainous a face as any they had ever seen.

The man was trembling with fear.

It was plain he was an arrant coward.

When the detectives looked him over, Old King Brady asked him:

"Say, what's your name?"

"Nick Wiffles."

"Where do you live?"

"In de swamp."

"Ain't you the man who built a bonfire on the railroad track some time ago, to stop a train from running into an obstruction?"

"I is."

"And you did it to stop the train?"

"He done telled me ter do it, boss."

"So you could steal a box containing Mr. Dalton's body from the baggage car during the confusion?"

"Dat's about de size ob it."

"And you got Dalton's body out of the box and carried it into the swamp?"

"I did."

"Into the hut?"

"Yassah."

"Were you alone?"

"All alone."

"When you got the body in the hut, what did you do with it?"

"I ain't a-gwine ter tell yer."

"All this was prearranged between you and Mason, wasn't it?"

"Yassah."

Old King Brady smiled. He had cleared up another mystery.

CHAPTER XIV.
EXPOSING THE SWAMP MYSTERY

The Bradys were surprised at the prompt manner in which the negro answered the questions put to him. But they presently observed that he was keeping a wary eye upon their revolvers, and evidently feared to get shot if they caught him lying to them.

Moreover, Old King Brady showed plainly by the questions he asked that he was familiar with the true inwardness of the things he accused Nick of. It made the darky think the old detective knew more about the case than he actually did know.

Seeing his advantage, Old King Brady said:

"Now, see here, Mr. Wiffles, you know we are detectives, don't you?"

"Ob c'ose," admitted the coon, in gloomy tones.

"You tried to shoot us, and you tried to kill us in the quick-sand. That gives us the right to put you on trial for your life, charged with attempted murder. You are in a pretty bad fix, old man. I wouldn't give two cents for your life. You know what little evidence is required here to hang a Georgia nigger. Therefore you can realize what your fate will be."

Nick began to cry.

Big tears rolled down his cheeks.

Falling on his knees, he cried in despairing tones:

"Oh, massa officer, hab mercy on me!"

"We are inclined to pity you, as you were merely an ignorant tool in the hands of a very wicked man. But of course you can't expect us to be lenient unless you aid us to capture Ronald Mason, and recover Mr. Dalton, either dead or alive."

"What yo' want me ter do, boss?" eagerly asked the miserable coon.

"Tell us where to find Mason."

"He lib in dat hut in de swamp."

"Why does he live there?"

"So's he kin watch his prisoner."

"Who is that – Mr. Dalton?"

"Yassah."

"Oh! Then he's got Dalton in the swamp, eh?"

"Fo' suah, boss."

"In the hut?"

"Dat's whar he was."

"Why is Mason holding him a prisoner?"

"Dunno. But I 'spects it's kaze he am a-tryin' fo' ter git de ole man ter sign a paper, an' de broker won't do it."

"What sort of a paper?"

"A bank check."

"I see. He wants to get a genuine signature to it."

"Wants all ob Massa Dalton's balance what am left in de bank."

"How much does it amount to?"

"Ober $75,000."

"Dalton refuses?"

"Obstinate as a mule."

"I don't blame him. Now, where is Dalton kept hidden?"

"Dat I can't say, boss. Somewheres in de swamp."

"Is Mason forcing Dalton?"

"Torturing de ole gemman."

"What a shame! Now, tell me: On the night you got Dalton from the box, was the old gentleman drugged?"

"Only tied hand and foot an' gagged."

"Then he was uninjured?"

"Only half starbed."

"When you carried him into the hut, he 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," exclaimed the girl, petulantly. "I can get you all the help you may need."

"Let us work our own way," quietly answered the boy. "Knowing that we've captured Nick, and may have pumped him, Mason will very likely be on the lookout for us, and meet us with a hot reception. By waiting, it will lead him to think we don't know anything about his subterranean abode. Then, when we attack, we will have a better chance of taking him by surprise."

The girl pondered a moment.

Cool reflection showed her the wisdom of Harry's plan.

"You are right," she admitted, reluctantly. "I'm so anxious to have something done for my poor father's instant relief that I can hardly suppress my impatience, though."

"We understand your feelings in the matter," replied Old King Brady, quietly. "But we know best how to handle your cousin. If you will leave the matter to our judgment, we will stand a better chance of making a success of our plans."

It required no argument to convince the girl, and she sighed, and said:

"Very well, Mr. Brady. Do as you think best. All I ask is that you will not lose any time about going to my father's rescue."

They discussed the matter fully that night.

In the morning the detectives returned to the swamp.

A careful examination was made of the dreary waste of mud and water, but they failed to see any signs of their men.

It was a bright, sunny day, but a dense vapor hung over the marshy land, and the officers went through it to the island.

They expected by coming so early in the morning to catch their enemies sleeping. But a discovery Harry made dispelled this idea.

He caught view of a tiny stream of smoke rising from some rocks.

Upon examining the spot, he found a natural chimney coming up through the ground, out of which the smoke was pouring.

When he returned to his partner and told him about it, he said:

"That's evidence enough that there's a cave under the island, and the column of smoke shows that Mason and the valet have started a fire to cook their breakfast. When we get in, we are likely to find them at that occupation. Are you ready for the attempt?"

"Certainly," assented Young King Brady.

They walked over to the hut, and entered.

Nick had explained where the trap was located, and they soon found a cunningly hidden ring, and pulled it upward.

A door, covered with earth, was raised.

It revealed a flight of damp stone stairs.

The Bradys drew their pistols, got their dark lanterns ready for use, and descended the stairs for a distance of fifteen feet.

They found themselves in a big natural cavern, and as they flashed their lantern lights around in the gloom, a cry of the most intense astonishment burst from their lips.