When two suspicious plane accidents occur near an eastern airport, the two Hardy brothers investigate the case and find themselves in greater danger than they anticipated.

The Hardy boys dial a wrong number, get the Pentagon, and suddenly find themselves in a dangerous adventure involving national security. Frank and Joe Hardy become involved in a case affecting national security when Joe dials a wrong telephone number and gets the Pentagon. Two words -- "Bombay boomerang"--That the boys hear before the line goes dead plunge them into a whirlpool of danger and intrigue. At the same time, their father is investigating...

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.

During their father's investigation of a ruthless gang of terrorists, two young detectives face several adversaries.

In the Northwest Territories of Canada, the Hardy brothers and Chet Morton help to recover a stolen Viking relic.

While investigating the theft of a valuable idol, Frank and Joe enounter a terrified business woman, a walking mummy, and a weird glass eye.

The Hardy brothers interrupt their investigations of jewelry-store holdups to answer a plea from their cousin on a New Mexico cattle ranch.

"Frank and Joe are excited for the school's annual talent show! Frank is working backstage, and Joe is going to show off his sweet juggling skills. Someone keeps playing pranks on all the acts-- bubbles are found in someone's trumpet and someone's music is replaced with the sound of croaking frogs!"--Jacket.

A disappearing floor, a savage-looking hound, a galloping ghost and a startling invention are just a few of the strange elements that complicate Frank and Joe's efforts to solve the mystery of the death of an heir to a mansion.

The Hardy boys travel to the Deep South to vindicate a long-dead Confederate general, disgraced during the Civil War because he was accused of stealing hidden gold belonging to a bank.