One cold autumn night, a woman is found hanging from a beam at her holiday cottage. At first sight, it appears like a straightforward case of suicide; María had never recovered from the death of her mother two years previously and she had a history of depression. But then the friend who found her body approaches Detective Erlendur with a tape of a séance that María attended before her death and his curiosity is aroused.

Driven by a need to find answers, Erlendur begins an unofficial investigation into María's death. But he is also haunted by another unsolved mystery - the disappearance of two young people thirty years ago - and by his own quest to find the body of his brother, who died in a blizzard when he was a boy. Hypothermia is Indridason's most compelling novel yet.