Plot summary (original edition)

The story begins with the Hardy boys and their pal Chet Morton returning to Bayport on a small coast liner from Larchmont where they had procured handwriting samples from Miss Pennyweather for a case their father Fenton Hardy was working on. During a storm, they meet Mr. Samuel Blackstone who tells the boys that he is carrying a large sum of money. Shortly thereafter, the ship runs aground and Mr. Blackstone is knocked down by Mr. Ruel Rand and badly hurt. Joe and Chet manage to swim to shore but Frank Hardy goes missing as he stayed behind to assist the injured Mr. Blackstone.

Shortly after Frank is located, the three boys are arrested on charges of robbing Mr. Blackstone. The Hardy boys immediately suspect Mr. Rand of robbing Mr. Blackstone and set out to track him down. Recording the license plate of a car that they see him get in to, they learn he lives in Hidden Harbor. The Hardy boys visit the wreck of the Resolute where they attempt to retrieve the handwriting samples. However, their boat drifts off and they are detained by the Coast Guard before they are able to reach their stateroom. After returning to land, they are questioned by the district attorney at Mr. Blackstone’s bedside. There they learn about the long standing feud between the Blackstones and the Rands.

Chet and the Hardy boys travel south to Hidden Harbor to retrieve new handwriting samples from Miss Pennyworth as well as to investigate who stole Mr. Blackstone’s money. While there, they are followed by a detective and their campsite is vandalized. They also stumble across a ‘secret society’ of young black men being led by Luke Jones, a servant to Mr. Blackstone. This group of Negroes kidnaps Mr. Rand’s mentally insane brother who manages to turn the tables on them by stealing their revolvers. Eventually the Hardy boys manage to find and disarm the brother as well as capture Luke Jones and make him confess to stealing Mr. Blackstone’s money and his diamond ring as well as being responsible for inciting more hatred between the two families. The Hardy boys also manage to gather indisputable evidence which solves their father’s case without the need for replacement handwriting samples.

Plot summary (revised edition)

The Hardy boys meet Mr. Bart Worth who is the editor of the Larchmont Record. He explains that Mr. Samuel Blackstone has sued him for printing a story accusing his ancestors of being pirates. Mr. Worth also tells the Hardy boys about the long standing feud between the Blackstone and the Rand families over ownership of a pond in Hidden Harbor.

The Hardy boys accept Mr. Worth’s case and, along with their friend Chet Morton, drive to Georgia. Once they have set up a camp on the beach between the two properties, the boys begin to investigate the Rand and Blackstone estates. They are surprised to find a ‘sea monster’ in the pond and to witness Mr. Rand being hit over the head with a vase by Mr. Blackstone, only moments later to find the vase intact and Mr. Rand missing.

Despite the efforts of their enemies, the Hardy boys manage to find Mr. Rand and recover a treasure chest containing historical records which prove that the accusations Mr. Worth made in his article were all true. The feud is settled when Mr. Rand and Mr. Blackstone decide to work together to harvest the valuable cypress trees from Hidden Harbor.

Original edition (1935)

• Ghostwriter: Leslie McFarlane (?)
• Summary: In the course of solving a robbery for which they were unjustly accused, the boys go to the South and end a long-standing family feud, solving a case for their father in the process.

Revised edition (1961)

• Revision type: Completely rewritten; only the central element of a family feud in the South is retained.
• Ghostwriter: James Buechler