When a lonely old man is found murdered 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, 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.