Bücher der Reihe Hardy Boys

When Frank and Joe join a volunteer project in the south of France, they hear that the ruined castle nearby may be haunted by the ghost of its lord, who was slain by bandits, and they wonder if the spooky events they witness are an attempt to sabotage their project.

An invitation from Cap Bailey, science teacher at Bayport High, to accompany him out West to Wildcat Swamp on an archaeological expedition triggers off a series of dangerous events for Frank and Joe Hardy. On their way West the boys and Cap have a near-fatal accident in a private plane which has been sabotaged. Though warned to leave the area, Frank, Joe, and Cap doggedly remain until they have caught the cunning ex-convicts they are up against in this swift-paced adventure.