John Vinge is a lonely cop who tries to discover the mysterious killer slaughtering families out at the Swedish forests.
The killer is wearing an African mask, the mask of Moon God.
He tries to confuse police's research while sending them a video with his actions.
John is forced to collaborate with doctor Erland but he doesn't like him at all.
John's father, en ex cop who is not satisfied with John's work and he always yelling on him. He is ill into the hospital and has a secret relationship with the doctor.
John is trying to find more details inviting a museum and asking for help a specialist in African culture and civilization. But the woman working there has a strange guy as an assistant who is looking for the same thing, the mask of Moon god.
Who is the killer and who keeps terrifying secrets about the past?
This cult Swedish film was lost for almost twenty years and this is the reason I couldn't find any trailer.
But it's a cool gem blending Giallo movies genre with slasher and mystery.