Fanny and Niko Grewe have breakfast at a lovingly laid table. Suddenly a siren sounds. Blue light. And then they discover: A dead woman lies in the garden. The dead woman found a neighbor: Marie Lehmann. She cannot muster much pity for the woman's death. Because of Ulla Seifert, Marie Lehmann lost her livelihood as a childminder. Did she take revenge for it? Fanny Grewe is the daughter of the dead Ulla Seifert. She lies completely confused in the arms of her husband Niko. A strange couple. They move like twins. Always know everything about each other. When they enter Ulla Seifert's apartment with Commissioner Luna Kunath and her new colleague Tamara Meurer, it smells of cigarette smoke. According to Fanny Grewe, her mother was a non-smoker. And then there's DNA from two unknown people. ...