On her 60th birthday, a woman dies by suicide. When the case lands on Detective Carl Morck's desk, he can't imagine what this has to do with Department Q, Copenhagen's cold cases division.

It's a tragedy to be sure, but the cause of death seems to be clear. But his superior, Marcus Jacobsen, is convinced that this is not in fact a suicide, but a murder related to an unsolved case that has been plaguing him since 1988.