The murder was meant as a punishment - but what sin could justify the method? The only person who might have answers is the victim's seven-year-old daughter, found hiding in the room where her mother died. And she's not talking. Newly promoted, out of his depth, detective Huldar turns to Freyja and the Children's House for their expertise with traumatised young people. Freyja, who distrusts the police in general and Huldar in particular, isn't best pleased. But she's determined to keep little Margret safe. It may prove tricky. The killer is leaving them strange clues: warnings in text messages, sums scribbled on bits of paper, numbers broadcast on the radio. He's telling a dark and secret story - but how can they crack the code? And if they do, will they be next?