Having rested awhile, the two boys started to get ready for their swim.  Both had just thrown off their coats, when there came a sudden cry from up the river.

“What’s that, Tom?” questioned Sam.

“Somebody is calling.  Listen!” and then both boys strained their ears for what might follow.

“There!  Stay where you are!  Don’t move!”

“I can’t stay here,” said another voice.

“Shall I shoot him now?” put in a heavy bass voice.

“No, wait a minute, I am coming over,” said still another voice, and then there was silence.  The Rover boys looked at each other in amazement.  What did the talk mean?

“Say, sounds to me as if somebody was in trouble!” exclaimed Sam.

“Perhaps we had better go and see,” returned Tom.

“All right, but we don’t want to get into trouble ourselves.  Those fellows, whoever they are, or at least one of them, seems to be armed.”

“We’ll take a few stones along, Sam, and a couple of sticks, too, if we can find them.”

Stones were to be had in plenty, and having picked up several of them, and cast their eyes around for a couple of clubs, the lads lost no time in making their way towards the spot from whence the voices had proceeded.  This was at a point where the river made a turn and was divided by a long, narrow island into two channels.  The island was covered with brushwood, while the banks of the stream were lined with overhanging trees.

“Now, I am going to shoot him!” cried one of the voices which the boys had heard before.

“No, don’t do it, just wait a minute!” answered some one else.

“Maybe they have got some poor fellow, and have robbed him,” suggested Sam, as he and his brother hurried forward as quickly as the trees and tangled brushwood would permit.

“One thing is certain, that fellow, whoever he is, is in trouble,” returned Tom.  “Perhaps we had better yell to those other fellows to stop.”

“If we do that, they may shoot the poor chap, and then run away.”

“That’s so, too!  Well, come ahead, let’s hurry and see if we can catch sight of them.”  And then the two boys pushed ahead faster than ever.

Presently the youths came to where there were a number of high rocks covered with trailing vines.  As, to avoid these, it would have been necessary to wade in the stream, and thus get their shoes and stockings wet, they began to scramble over the rocks with all possible speed.

“Listen!  They are talking again!” exclaimed Sam.

“Grab him!  Grab him by the throat!”

“That’s all right, Jim, but I don’t want the boat to upset,” growled another voice.

“Say, you fellows make me tired!” roared the heavy bass voice.  “Do you want to keep us here all day?”

“What do you know about this gun?  Maybe it will explode.”

“Say, Sam, I don’t know what to make of this!” panted Tom, who was almost out of breath from the violence of his exertion.