Explaining that there are gold bars buried in her childhood backyard, Mrs. Rilke asks the Hardy boys to recover the treasure for her when they travel to Lisbon, Portugal.

It's winter in Bayport, but things are heating up at the Morton family farm. It looks like someone is wreaking havoc with the property, and Chet and Iola Morton are worried that their grandparents are in danger of losing it! With their parents out of reach, the Mortons call on Frank and Joe Hardy for help. They need to figure out who's behind the trouble -- and fast. The Hardys are hot on the trail, but the Mortons' grandparents do something unexpected...

The Hardy Boys are given clues which send them in search of the treasure hidden by the Outlaw of the Pine Barrens. Unfortunately, the person who wrote the clues, like the silver he stole, has been buried for over 200 years.

The Hardy boys investigate when the Fire Creek Mountain Race in Quebec is sabotaged by "accidents."

The Hardy brothers' visiting Greek pen pal enlists their help in searching for a priceless ancient Greek helmet loaned to and lost by a Hollywood movie company years before.

The Hardy brothers travel from the highways of eastern United States to tropical islands trying to track down truckloads of precious cargo that are being hijacked.

Frank and Joe are confronted with the crisis of water disappearing from the reservoir at Skull Mountain.

Chet Morton is kidnapped the first day of his new job driving an ice cream truck, and the Hardys must track down the kidnappers.