A renowned pianist is found murdered, and the detective Cato Isaksen and his colleagues are facing murder victim number four. The man is killed with deep stab wounds and his throat slit, in the same way as the previous three men. Under the body there is a mysterious note extracted from the children song "Sleep you little sprout young". More and more evidence points to the women of the slain men, but where's the common denominator? On the home front Cato miss the family life with Bonnie and the kids a little bit more than is good. Cohabitants Sigrid is obviously furious when she finds out what's going on. At the same time she is really getting along with the psychologist Sonja Pettersen. The two are planning a trip to the mountains together where Sonja will learn Sigrid to find their inner power. With the ride is also Sonja's colleague at the shelter and little Georg. As Cato Isaksen thinks he has found the solution to murder mystery, the story twists in an unexpected way.