Gothenburg is struck by a series of fires. Irene Huss starts investigating an arson case that may be connected to an event that occurred fifteen years ago, a tragic unsolved case that challenged Irene when she first came to the Violent Crimes Unit. The population is unnerved by the thought of an arsonist on the loose, and the pressure on Irene and the rest of her team is immense. In the midst of everything else, a woman has been stabbed to death. The victim, a reclusive old lady, seems to have little in common with the fires that ravage the mainland.