Franklin W Dixon

Fenton Hardy, the famous private detective and father of the Hardy Boys, asks his sons to help him with his latest case involving the illegal drug trade. Hardy sends Frank and Joe to a house on the cliff, whose location offers an excellent vantage point to watch for smugglers. The Hardy Boys are tricked into going inside the house by cries for help and find themselves trapped for a short time in the attic, meanwhile, their telescope and motorcycles...

Joe Hardy is kidnapped by a gang of jewel smugglers as a warning for the Hardy Boys' father to stay away from their operation.

The Hardy brothers try to find out who is behind a rash of automobile thefts that are occurring on Shore Road just outside of Bayport.

Frank and Joe attempt to foil a ruthless espionage ring in their effort to sabotage the United States space program.

The search for a stolen boat leads the Hardy brothers to Mexico where they become involved with a band of Indians and a strange smuggling operation.

The search for missing gold takes the Hardy boys to the Yucatán Peninsula where they uncover a second mystery.

After the new hydrofoil they are guarding is stolen, the Hardy boys face frequent danger in solving a mystery involving criminals who operate by signs of the zodiac.

An archaeological expedition in the West turns into a desperate attempt to capture robbers and an escaped convict.