Panic on Gull Island (The Hardy Boys, No. 107)

Terror is sweeping across the peaceful resort community of Gull Island, Florida, and Frank and Joe may be too late to stop it. A rash of robberies and acts of vandalism have sent many residents fleeing, leaving a greedy real estate agent to gobble up their properties at low rates. And when Joe's girlfriend is kidnapped, they know they're up against a dangerous mob of gangsters.