atching his head once more, Tom
concluded that he had made a mistake.

"I'm upset if ever a fellow was," he thought. "Well, no wonder. Such
happenings as these are enough to upset anybody."

Tom knew of nothing more to do than to return to where he had left
Dick, and this he did as quickly as the tired horse would carry him.

"No success, eh?" said the oldest Rover. "What do you make of it, Tom?"

When he had heard his brother's tale he grew unusually grave.

"You are sure you heard them scream?" he questioned, anxiously.

"I'm sure of nothing--now. I thought I was sure about the houseboat, but
I wasn't," answered Tom, bluntly. "I'm all mixed up."

"I'll go down there with you," was the only answer Dick made.

It did not take long to reach the spot. It was now dark and a mist was
rising from the river.

"This is certainly the spot where we tied up," declared the oldest
Rover. "Why, I helped to drive that stake myself."

"Then the houseboat is gone!"

"That's the size of it."

"And the girls are gone too," went on Tom. "Yes, but the two happenings
may have no connection, Tom."

"Don't be so sure of that!"

"What do you mean?"

"I'm thinking about Dan Baxter and Lew Flapp. They wouldn't be above
stealing the houseboat."

"I believe you there."

"And if those girls happened to go on board--Look there!"

Tom pointed out in the darkness on the road. Two horses were coming
toward them, each wearing a lady's saddle and each riderless.

"There are the horses," said Dick. "But the girls? You think--"

"The girls came down here on their horses and dismounted, to go on
board of the houseboat."

"Well, where is the houseboat?"

It was a question neither of them could answer. They looked out on the
river, but the mist hung over everything like a pall.

"Dick, I am afraid something serious has happened," came from Tom,
ominously. "Those screams weren't uttered for nothing."

"Let us make a closer examination of the shore," answered the oldest
Rover, and they did so. They found several hoofprints of horses, but
that was all.

"I can't see any signs of a struggle," said Tom.

"Nor I. And yet, if those rascals ran off with the houseboat and with
the girls on board, how would they square matters with Captain Starr?"

"And with Captain Carson? The tug is gone, too."

"Yes, but the tug went away when we did, and wasn't to come back until
to-morrow morning. Captain Carson said he would have to coal up, ove