A pyromaniac is on the loose and terrorizing the streets of Gothenburg for the past 2 months. The case starts to take a dramatic turn when the first fatality is reported and Irene is summoned to help her colleague Birgitta hunt the culprit down. Their only lead? All the targeted places are addressed Number 9… At the same time, Irene is called upon another case in which a lonely reclusive old lady from an islander close-knit community, Ingrid Eriksson, has been found stabbed in her house.