Teenage detectives Frank and Joe Hardy investigate a case of counterfeiting.

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

When thieves hijack a collection of stuffed animals from a country auction, Frank and Joe Hardy pursue the getaway car and are drawn into a thrilling mystery. The recently acquired interest of their best pal, Chet Morton, in taxidermy as a hobby adds fresh twists to the puzzle. At the same time, the young detectives' father -- famed private investigator Fenton Hardy -- is tracking down an industrial spy ring. Over the Hardys' ham radio, Frank and...

The Hardy boys and two friends take a camping trip to the Rocky Mountains in an attempt to locate a gang of credit-card counterfeiters.

Helping in a case their father is working on, the Hardy boys try to find an informer who has telephoned from a booth in their home town, and are hired by a carnival owner to spot pickpockets.

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

When the Hardy boys buy a Chinese junk (ship) for a money-making venture, they discover it has a serious flaw.

A chance meeting with a stranger on the road provides the Hardy boys with a clue to a gang of local burglars.

In trying to trace a missing will, detectives Frank and Joe Hardy trap a dangerous criminal who is willing to risk all--including murder--for money.

In an effort to recover a top-secret instrument needed by the space program, the Hardy boys travel to South America, hot on the trail of a notorious ring of spies.