To those who have read the previous volumes in this “Rover Boys Series” of books, the lads we have just met will need no special introduction.  For the benefit of my new readers, however, let me state that the Rover boys were three in number, Dick being the oldest, fun-loving Tom coming next, and Sam being about a year younger still.  When at home they lived with their father, Anderson Rover, and their Uncle Randolph and Aunt Martha on a beautiful farm called Valley Brook, in New York State.

Years before, and while their father was in Africa, the three boys had been sent by their uncle to Putnam Hall Military Academy, as related in detail in the first volume of this series, called “The Rover Boys at School.”  At the Hall they had made a number of friends, including Songbird Powell and the dudish student, William Philander Tubbs.  They had also made some enemies, who did their best to bring the Rover boys to grief, but without success.

A term at school had been followed by a short cruise on the ocean, and then a trip to the jungles of Africa, whither the lads went to find their father, who had disappeared.  Then, during vacation, the boys took a trip West, and then another trip on the Great Lakes.  After that they went in the mountains, and then came back to Putnam Hall, to go into camp with their fellow cadets.

This term at Putnam Hall was followed by a long journey on land and sea, to a far-away island of the Pacific, where the boys and their friends had to play “Robinson Crusoe” for a while.  Then they returned to this country, and, in a houseboat, sailed down the Ohio and the Mississippi Rivers.  After leaving the Mississippi they took an outing on the plains, and then went down into southern waters, where, in the Gulf of Mexico, they solved the mystery of a deserted steam yacht.

“And now for home and a big rest!” said Dick, and they went back to the farm.  But here something very unusual occurred, and the boys had as lively a time as ever.

While at school the three Rover boys had become well acquainted with three girls, Dora Stanhope and her cousins, the two Laning sisters, Nellie and Grace.  Dora was the only daughter of Mrs. Stanhope, a widow, and soon she and Dick became the warmest of friends, while Tom was quite taken by Nellie, and Sam often “paired off” with Grace.

In those days Josiah Crabtree had been an instructor at Putnam Hall.  He was very dictatorial, and none of the cadets liked him, and the Rovers liked him still less when they learned that he was trying to practically hypnotize Mrs. Stanhope into marrying him, so that he could get control of the fortune which the widow was holding in trust for Dora.  They foiled the teacher’s efforts to wed the lady, and in the end Josiah Crabtree had to leave Putnam Hall.  Later still he was arrested for some of his misdeeds and given a short sentence in jail.

The Stanhope fortune, as a part of the money coming to the Stanhopes and the Lanings was called, had come to Mr. Stanhope in a peculiar way, and some outsiders claimed the treasure, which, at that time, was secreted in a spot among the West Indies called Treasure Isle.  There was a lively chase to get there first, but the Rovers won out, and because of this their enemies were more bitter than ever.