Johan is on conditional discharge, Minnie has lost custody of her daughter due to drug abuse, and they join a group for therapy on an isolated island in the archipelago. An island with a dark history.
No evidence is found, but Minnie’s sense of a supernatural presence in room 5 grows, and she is warned by the housekeeper, Gittan, not to delve too deeply into the island’s past. Johan frantically tries to recover his phone and computer, which have been confiscated by Uno, leading Uno and assistant Agnes to keep a watchful eye on him.
The circumstances surrounding the woman who disappeared on the island become more mysterious and Minnie wants to go into Room 5 seeking answers. Uno puts more pressure on Johan which frustrates Johan’s desire to leave the island and complete the business deal his father wants him to sign.
Minnie’s relationship with Uno becomes increasingly intimate and complicated, while she and Johan find evidence to suggest that Uno is guarding some dark secrets from the past. The intrigues escalates when the group goes out for a hike in the wilderness.
Minnie is convinced there is a darkness on the island, and she connects it with the name Maja. Perhaps the answer lies in the empty cholera hospital on the other side of the island, but dark forces are determined to preserve the secret. Minnie thinks that Maja is there or, rather, that it was there she was murdered.
The theories about who or what lies behind the horrible events in Svartsjön differ greatly. Is it possible that the current disappearances are related to what happened 70 or 160 years ago? Is it an evil curse or does the real threat come from Dag, Jostein and Erkki?
Oskar has vanished but Uno doesn’t want to tell the police straight away. As the group search for him, the tragic past of the island is revealed. Minnie finds out more about Maja, leading her back to the cholera hospital where someone, or something, seems to be waiting for her.
Who has stolen all the mobiles and cut the telephone lines to the mainland? It seems clear that someone in the group is a killer, and does not want the others to leave. Minnie believes that she knows what is hunting her, and that it can be found in the old lighthouse.