After securing a grant to study stellar structures, American applied mathematician David Sumner moves with his glamorous young Cornish wife Amy to her home village of Wakely in the Cornish countryside. Amy's ex-boyfriend Charlie Venner, along with his cronies Norman Scutt, Chris Cawsey, and Phil Riddaway, immediately resent that the meek outsider has married one of their own. Scutt, a former convict, confides in Cawsey his jealousy of Venner's past relationship with Amy. David meets Venner's uncle, Tom Hedden, a violent drunkard whose flirtatious teenage daughter Janice seems attracted to Henry Niles, a mentally deficient man despised by the entire town.