Detective Huldar and child psychologist Freyja have little in common except for the young girl who’s been traumatized after witnessing her mother’s murder.

The murderer leaves behind a paper with numbers at the crime scene. Is it a cipher or a message? The case grows more tangled when the numbers start turning up elsewhere.

Another victim is found brutally murdered, and Huldar and Freyja make unexpected connections that bring them closer both to solving the case and to the prime suspect.

All signs point to a man held in custody, but Huldar isn’t convinced of his guilt and presses on with the investigation, just as a young man disappears without a trace.