Good condition, especially for its age. Published 1969. General wear on cover. A few pen marks on the spine. Yellowing and age spots on pages but no other markings. '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.'