Pétur is an optometrist happily married to Ásta. They are expecting a child but already have a 10 year old boy named Örn. On coincidense Pétur finds out that he is not Örn's biological father.

Arnaldur, a 16-year-old boy living a normal teenager's life in Reykjavik. One day, coming home from school, he finds his brother in the bathtub, dead. Despite clear signs of a suicide, Arnaldur is convinced that his brother's teacher is somehow responsible so he decides to take matters into his own hands and avenge his brother.