When a lonely old man is found dead in his Reykjavik flat, the only clues are a cryptic note left by the killer and a photograph of a young girl's grave. Inspector Erlendur discovers that many years ago the victim was accused, but not convicted, of an unsolved crime, a rape. Did the old man's past come back to haunt him? As Erlendur reopens this very cold case, he follows a trail of unusual forensic evidence, uncovering secrets that are much larger than the murder of one old man.