Irmgard Wernicke (Barbara Morawiecz) lives alone in a small rented apartment. The elderly retiree talks to her budgies, watches TV and watches the factory floor across the street. One morning, the homicide squad received Mrs Wernicke's call for help: she firmly asserted that a woman had been murdered in the house across the street. Ritter (Dominic Raacke) and Stark (Boris Aljinovic) talk to the old lady and a little later start investigating at the alleged crime scene. The wine merchant Benkelmann (Hans-Jochen Wagner), who lives there, provides friendly information – but there is no corpse or traces of a murder. Nevertheless, Ritter and Stark are more and more fascinated by the portrayal of the amiable old woman, who reminds Ritter of his mother.
The inspectors also get to know Mrs. Wernicke's nurse Renate Müller (Lotte Ohm) and the civil servant Timo (Robert Höller) - the only people with whom she has close contact. When it came out that Ms. Wernicke saw Hitchcock's film "Window on the Courtyard" on television on the alleged night of the murder, doubts arose: did the old lady get infected and just make up her statements? But why is Benkelmann trying to hide contact with the attractive Ella Leiser (Jenny Schily)? Shortly thereafter, Irmgard Wernicke disappears, but female body parts appear. Knight and Stark are dismayed. Did they misjudge the situation and should they have protected the old lady?