Chief Inspector Bernd Krallert from the Cologne CID has absolutely no idea that his whole life is about to be thrust into turmoil. As part of an international police exchange programme the talented Japanese detective Ushiro Sato turns up at the city on the Rhine, and Krallert finds himself welcoming his new partner not only into his office but also into his house. Yes, Krallert's home life is also turned upside down, since Sato is to move in without delay... and more or less become one of the family.