Frank has no choice but to side with his grandmother and play her game if he wants to get close enough to destroy The Eye. Fenton returns to Bridgeport with Rupert Khan and learns that Joe and Frank have gotten themselves farther along in their investigation than he could imagine. But when Fenton tries to get Frank to leave the Estabrook Estate, his son refuses. Spurned by Frank, a revenge-seeking Stacy puts one of Frank's friends in danger.
After a family tragedy strikes, Frank Hardy, 16, and his brother Joe, 12, are forced to move from the big city to their parents' hometown of Bridgeport for the summer. Staying with their Aunt Trudy, Frank and Joe's quiet summer quickly comes to a halt when they discover their dad, Detective Fenton Hardy, has taken on a secret investigation. Realizing that their Dad may be on to something the boys take it upon themselves to start an investigation of their own, and suddenly everyone in town is a suspect.