An elderly man is found murdered in his basement flat. Inspector Erlendur and his crew don´t have much to go by in the investigation, but a photograph of a young girl´s grave gives them a lead. They discover that many years ago the victim was accused, though not convicted, of horrible crimes. 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 – with clues knit into the genetic bloodline of an entire country.