The Secret of the Island Treasure

The Hardy Boys Secret Files Collection Books 1-5

The Twin Dilemma

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)

Britfield & The Rise of the Lion

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

The Mystery of the Cranky Collector

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

The Twin Dilemma

Franklin W. Dixon, Carolyn Keene, 1993

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

Britfield & The Rise of the Lion

C.R. Stewart, 2021

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

Hayley LeBlanc, 2022

The Mystery of the Cranky Collector

M. V. Carey, Mary Carey, 1987