The Secret of the Island Treasure

The Hardy Boys Secret Files Collection Books 1-5

Danger Overseas (Nancy Drew: Girl Detective and Hardy Boys: Undercover Brothers Super Mystery #2)

The Gross Ghost Mystery (Frank and Joe Hardy: The Clues Brothers #1)

The Hayley Mysteries: The Missing Jewels (The Hayley Mysteries, 2)

The Case of the July 4th Jinx (Milo and Jazz Mysteries)

The Secret of Spiggy Holes

The Absent Author (A to Z Mysteries)

The Hardy Boys

In The Secret of the Caves, the Hardys face a trio of rogues. While investigating a string of false clues, the Hardy boys, along with their friend Chet, are able to solve the mystery and reunite a long-lost family member with their rightful inheritance.

Discover Your Child's Next Read

The Secret of the Island Treasure

Franklin W. Dixon, 1990

The Hardy Boys Secret Files Collection Books 1-5

Franklin W. Dixon, Scott Burroughs, 2014

Danger Overseas (Nancy Drew: Girl Detective and Hardy Boys: Undercover Brothers Super Mystery #2)

Franklin W. Dixon, Carolyn Keene, 2008

The Gross Ghost Mystery (Frank and Joe Hardy: The Clues Brothers #1)

Franklin W. Dixon, 1997

The Hayley Mysteries: The Missing Jewels (The Hayley Mysteries, 2)

Hayley LeBlanc, 2022

The Case of the July 4th Jinx (Milo and Jazz Mysteries)

Amy Wummer, Lewis B. Montgomery, Mara Rockliff, 2010

The Secret of Spiggy Holes

Enid Blyton, 1940

The Absent Author (A to Z Mysteries)

John Steven Gurney, Roy Ron, 1997