In the middle of the abandoned Swedish swamps is the village of Mossmarken, where people have come since ancient times to leave offerings to the gods. The village holds terrible secrets, because for many years local residents disappeared in the ominous swamps of Mossmarken. They were found a few years later with a bag of coins in their pocket. The young biologist Natalie Strem, for the sake of research for her dissertation, returns to her once native place, from where she left after a terrible family tragedy. There she meets Johannes, a student at a local college. One night, after a storm, in a swamp, she finds her new friend unconscious, and in his pocket there is a scattering of gold coins, next to it is a fresh grave. This find provides a chilling excuse to start researching the past - for both the police and Natalie. Is the swamp hungry for more victims, as locals claim? Or is the terrible evil that lurks in this small village human in nature?