Die Sitte: Kaltes Blut.

A 14-year-old girl is found murdered in the park. As the police suspect a sexually motivated crime, ‘Die Sitte’ is called in - a special squad of the criminal investigation department. Public prosecutor Marion Brandt, detective Hannah Koch and detective Leonard Winkler question the family and investigate the dead girl's circle of friends. Behind the façade of an ideal world, they come across a thicket of feelings of hate, love, envy and jealousy.