Emma, an art expert at a prestigious auction house, is dispatched to a small island near Stockholm to evaluate the Gussman family estate in their "haunted" mansion.
In 2012, a teenage girl was found hanging from a tree of the estate, her thighs slashed, her big toes tied together, a pair of scissors dangling from her neck.
Soon after Emma's arrival nine years later, another murder takes place on the island. All signs seem to point to the same killer.
When Emma finds a note saying "HELP ME I'M LOCKED IN HERE," she realizes the worst has come to pass.
She and Commander Karl Rosén are caught up in a spine-chilling investigation involving viking rituals, madness, and dark love affairs.