A man is found murdered in his Reykjavik flat. There are no obvious clues apart from a cryptic note left on the body and a photograph of a young girl's grave. Delving into the dead man's life Detective Erlendur discovers that 40 years ago he was accused of an appalling crime, but never convicted. Had his past come back to haunt him? As Erlendur struggles to build a relationship with his unhappy daughter, his investigation takes him to Iceland's Genetic Research Centre, where he uncovers disturbing secrets that are even darker than the murder of an old man.