After intervening in a fist fight and getting beaten up herself, Maria heads the investigation of a woman who was murdered close to the place where Maria was assaulted. The murderer most likely witnessed what happened to Maria. The motifs oscillate between revenge for infidelity and hatred towards homosexuals, and as the number of murders increase so does Maria's frustration over the reluctance from neighbors and potential witnesses to collaborate in the investigation.

Just as the Medieval Week is about to begin in Visby, the seventy year old woman Frida is assumed dead in an arson. When several murders occur, the traces lead Maria Wern and her colleagues to a quaint village where everyone knows everyone. The discovery of some documents in Latin and incomprehensible drawings turn the police's suspicions towards the rituals of the Medieval celebrations.