A woman murderer kills a woman every year during the carnival in Cologne. Fabel goes hunting with his partner. This pursues completely different goals.

Carnival in Cologne - people are dancing in the streets and the only thing that counts is having fun. But for Chief Inspector Benni Scholz, the happy masquerade has now become a nightmare: he has two unsolved murders in his files, committed in the last two years on the same day: Women's Carnival. Scholz fears that the murderer will strike again this year and calls in the expert on serial killers: Jan Fabel from the Hamburg Homicide Squad. But there are completely different reasons why Fabel actually travels to Cologne to provide support: his traumatized colleague Maria is in Cologne on a revenge campaign against the unscrupulous underworld boss Vitrenko. Since Maria was stabbed in cold blood by Vitrenko during a police operation, her life has been thrown into disarray. She wants to bring Vitrenko down, whatever the cost. In her merciless desire for revenge, Maria knows no bounds - and finds herself in great danger. Fabel has to make a difficult decision: It is Women's Carnival - and the female murderer will also strike on this night.—ADR Das Erste