The Nightmare Man (1981)

A heavy fog cuts a small isolated Scottish island from the mainland, and dentist Michael Gaffikin has just discovered a dismembered corpse on the golf links. Gaffkin and his artist girlfriend assist local law enforcements in searching for the killer. However, as the body count rises and the surrounding circumstances turn increasingly bizarre and gruesome, everyone begins to wonder if the perpetrator is a human or an unimaginable creature.