When a shadow from the past reawakens, successful surgeon Axel Glenne's life turns upside down. Soon after, a woman's body is found in Nordmarka, a forest north of Oslo.

Items found near the body suggest that the killer is leaving a message, and while this death is being investigated, another woman is murdered. The similarities are too close to be coincidental - and it appears that Axel Glenne has a connection to both victims. Medusa is a Scandinavian psychological thriller about identity and jealousy, unfaithfulness and revenge.