Empathetic, meticulous and relentless - the only thing to escape Larvik detective William Wisting in his hunt for Norway's most notorious criminals is a happy family life. And when two mysterious deaths interrupt Wisting's Christmas, it is the beginning of a showdown with the deadliest killer of them all.
While recovering from a severe injury, Wisting receives an anonymous letter in the mail. The cryptic content leads Wisting to suspect a possible injustice in an old murder case where a 17-year-old girl was killed, and her ex-boyfriend was convicted.
A new anonymous letter leads to fresh evidence, but not everyone is happy to see the old murder case back in the spotlight. Wisting realizes he is being opposed by powerful forces within the police, as he keeps searching for the secret messenger.
A breakthrough in the case takes Wisting to Vilnius for a meeting with Interpol investigator Harriet Dunn. What is meant to be a simple questioning of a suspect becomes far more complex for both of them - both professionally and personally.
New DNA evidence appears to solve the murder of Tone, but Wisting still feels that something is amiss. Wisting and his colleagues must call on all of their skills and experience to avoid a dramatic and dangerous situation.
