"Next to a big swamp," replied Harry. "And, by Jove--see--see! There's an obstruction--a heap of sleepers piled across the rails beyond the bonfire."

"What the deuce can that mean?" muttered Old King Brady. "Bandits trying to rob this train? It don't seem possible, in this neighborhood."

The train paused and they all alighted.

Some of the brakemen ran ahead, and under the conductor's direction they removed the obstructions from the rails.

The fire seemed to have been built where it was to show the engineer the pile of sleepers, and the brakemen scattered it, when the barrier was removed.

As the bell rang, every one got aboard and the cars slowly went ahead.

The Bradys and the baggage master returned to the latter's car.

"We'll finish our examination of that body," said Old King Brady.

"Yes," said Harry, "and----Good gracious! Where's the box gone?"

Box and body had vanished.

Every one was astounded.

Then, like a flash, the truth suddenly dawned upon Harry's mind, and he cried:

"Now I see through it. Those obstructions were put on the rails to stop the train at this point so that the body could be removed from this car."

"By whom?" demanded the startled baggage master.

"Accessories of the villain who killed that man!" cried the boy.

"They've carried the body off in the swamp to hide the evidence of their crime. Come, Old King Brady, alight here and see if we can trace it."

The detectives made a rush for the door and leaped from the train.

They landed beside the roadbed, and the cars went on without them.

CHAPTER III.

THE GREAT SWAMP MYSTERY.

Heavy banks of dark clouds were flying across the lowering sky.

Occasionally the big silvery moon burst from the rifts and flooded the landscape with its mellow light.

During one of these intervals the two detectives gazed around.

The train had disappeared in the distance.

Not far away from where the Bradys stood they saw the big box lying beside the track, turned over on its side.

They ran back and hastily examined it.

"Empty!" e.j.a.c.u.l.a.t.ed Harry, in some surprise.

"What has become of the man it contained?" asked Old King Brady.

"Search. He may have fallen out."

They carefully examined the ground within a wide radius.

But they found nothing of the missing body.

"Mysterious, what became of him!" Old King Brady exclaimed.

Harry was completely at his wits' end.

"I'm afraid we are beyond our depth, Old King Brady," he remarked.

"This mystery keeps growing all the time, and we can't seem to fathom it."

Just then the moon appeared again.

It showed them a river on one side and a broad expanse of gloomy swamp land on the other.

Night insects were chirping amid the weeds, and frogs were croaking dismally among the waving reeds and rushes.

Off in the centre of the swamp were some tangled trees and bushes, heaps of rocks overgrown with moss and trailing vines, and an object which had the dim outline of being an old rookery of some sort.

It was a dismal, lonesome scene.

Young King Brady moved along the edge of the boggy ground with its little pools of water, tufts of coa.r.s.e gra.s.s and tracts of black, oozing mud.

An old, rotten board walk from the railroad bed to the trees, caught his view and he suddenly called to the old detective:

"I see a light among those trees. Here's a path. Let's follow it into the swamp."

"Be cautious!" warned the old detective. "If those rascals have carried the body from the box to the midst of those trees, they will be on the lookout for any possible pursuers and may give us a warm reception."

"We need not let ourselves be seen," replied the boy.

"How are you going to avoid it?"

"By creeping along the path on our hands and knees. The reeds on each side will hide our bodies from view."

"Go ahead, then."

They went down on their haunches and crept along in single file, out into the dismal swamp, and drew near the oasis.

In a few minutes they reached firm land.