Franklin W Dixon

When Mr. Hardy disappears while investigating a mystery surrounding a vacant house rumored to be either haunted or an abode for criminals, Joe and Frank search for the truth.

Frank and Joe unravel two mysteries, one involving a counterfeiting case and the other concerned with a national security case their father is working on.

Their SOS ignored in a storm, the Hardy boys find a wallet containing two thousand dollars alongside their boat and are launched into a mystery involving diverse clues.

The Hardy boys dial a wrong number, get the Pentagon, and suddenly find themselves in a dangerous adventure involving national security.

Through the course of the mystery they are confronted with the theft of the Jeweled Siva, a valuable Oriental idol; an innovative hydrofoil speedboat; a terrified wealthy businessman and a health farm run by a mysterious doctor.

When Frank and Joe investigate threatening notes and a secret room in an old mansion, robbery and mistaken identity complicate matters.

Frank and Joe go to the Pocono Mountains to investigate the mystery of a legendary witch who stalks Black Hollow seeking vengeance. Disappearances occur and strange screams fill the night.

When the Hardy boys eagerly agree to assist their friend Jack Dodd and his father in locating a family treasure, the two young detectives are unaware of the baffling complications that will arise. The only clue to the long-lost treasure is a cryptic message written by a Pilgrim ancestor. But when Mr. Dodd and Jack are accused of stealing cars and then mysteriously disappear, Frank and Joe are confronted with a triple mystery. Have their friends run...

Vicious traps and threats beset Frank, Joe, and Chet as they search for two stolen, famous paintings in an old fort said to be inhabited by a ghost. One of the paintings is a clue to the hiding place of a chain of gold.

When the Hardy Boys set out to solve the mystery of their missing chums, they discover a gang hide-out in a cave on an island along the way.