The Mystery of the Spiral Bridge (Hardy Boys, Book 45)

Frank and Joe Hardy are determined to bring to justice the vicious criminals who kidnapped their detective father while he was investigation sabotage of a road-building project in the Kentucky wilderness. After Mr. Hardy’s escape, the two young sleuths are spurred into action when he mumbles the word “Felix” and they discover a dossier of a notorious ex-convict was stolen from his files. The trail leads them to New York City but ends abruptly in a cemetery! With the new clue of a spiral symbol the boys head to Kentucky as part of a highway construction crew to track down the kidnappers and saboteurs.

• The Haunted Fort (Hardy Boys, Book 44)
• The Mystery of the Aztec Warrior (Hardy Boys, Book 43)
• The Secret Agent on Flight 101 (The Hardy Boys, No. 46)
• The Viking Symbol Mystery (Hardy Boys, Book 42)
• The Clue of the Screeching Owl (Hardy Boys, Book 41)
• Mystery of the Whale Tattoo (Hardy Boys, No. 47)
• The Arctic Patrol Mystery (Hardy Boys, No. 48)
• The Mystery of the Desert Giant (Hardy Boys, Book 40)
• Danger on Vampire Trail (The Hardy Boys, No. 50)
• The Bombay Boomerang (Hardy Boys #49) (The Hardy Boys)