After receiving an anonymous letter about a missing 12-year-old girl, devout Christian and dedicated cop Neil Howie (Woodward) travels by seaplane to a remote Scottish island to investigate. But the islanders welcome neither his badge nor religious devotion, for laird of the isle Lord Summerisle (Lee) and his devoted followers worship only the pagan gods of old - and those gods demand a sacrifice. Howie fears for the missing girl's life and follows every possible lead to find her - despite the islanders' interfering machinations - before she becomes a human sacrificial lamb.