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.

When Frank and Joe try to get hold of a top secret invention, they are put on the trail of jewel thieves and smugglers. Joe is kidnapped and Frank starts off on the chase.

Hired to locate an old Spanish cannon, the Hardy brothers uncover an even greater treasure after perilous underwater adventures.

Joe and Frank suspect there is a link between the counterfeiting case they are investigating, and the case their father can't discuss. Determined to learn the secret, the Hardy Boys get themselves into a scrape.

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.

The two Hardy brothers help their father search for stolen electronic parts.

Vicious threats and deadly traps beset Frank, Joe and Chet as they search for clues to the stolen paintings and the gold treasure--a search that is complicated by a stormy feud between a proud Englishman and an equally proud Franchman over the military history of the ancient fort.

When Frank and Joe Hardy are sent to a tropical island resort to investigate a string of thefts, they soon feel like missing jewelry is the least of their concerns--a sentiment echoed by Nancy Drew, Bess, and George who are staying at the same hotel as guests.

Nancy Drew and the Hardy Boys team up to investigate when a swimmer competing in the upcoming Summer Olympics starts receiving death threats.

While searching in Iceland for a missing sailor sought by an insurance company, the teen-age detective brothers uncover a plot threatening the life of a United States astronaut and the secrets of NASA's moon project.