After a family tragedy strikes, Frank Hardy, 16, and his brother Joe, 12, are forced to move from the big city to their parent's 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 onto something the boys take it upon themselves to start an investigation of their own, and suddenly everyone in town is a suspect.