When estate administrator Jana Welzer has the parquet flooring installed in the new office of her parents' house, the craftsman makes a gruesome discovery: beneath the wood, there are traces of a large bloodstain. With the help of her detective colleague Steffen Horndeich, it quickly becomes clear that it is human blood. The amount of blood suggests a serious violent crime must have occurred. The thought of setting up the new business in a place where a person was murdered disturbs Jana. Together with Steffen Horndeich, she tries to uncover the bloody secret. Horndeich and Jana delve into the history of the house and its tenants, uncovering secrets that perhaps should have remained hidden.