At a gas station in Mainz, the attendant is shot dead – the second robbery in two weeks, and this time a fatal one. The only witness to the crime is Rosa Münch, a blind law student who still lives with her parents and longs for a life free from her father's overprotective control. Ellen Berlinger and Martin Rascher investigate, following the trail of the two perpetrators and the clues provided by the blind woman: the scent of an expensive perfume, the voices of suspects, and details Rosa heard and felt at the crime scene. The detectives want to place the vulnerable Rosa under police protection, but the young woman refuses. On the contrary, when a young woman whose voice sounds familiar tries to contact her, she keeps it to herself. Ellen Berlinger and Martin Rascher suspect that Rosa knows more than she's letting on. The investigators must continue their work without her support and resort to unconventional methods to prevent further deaths.