A rich Frisian farmer has been murdered in Amsterdam and police duo Grijpstra & De Gier are sent to investigate. Adjutant Grijpstra has problems at home again and is happy to leave for Friesland to investigate the murder. Sgt. De Gier finds the Frisian Hylke much more interesting than the murder case. In Leeuwarden there is a real Chinese war and a brutal robbery at the cattle market. Suddenly there is that friendly rattling, asthmatic rat who provides an unexpected solution.

Fatal Error (1979) is a comedy crime thriller set in Amsterdam, Netherlands. The film follows a duo of buddy detectives who get entangled in a dangerous plot involving deception, drugs, and murder. As they investigate the murder of a nude woman, they uncover a web of intrigue that leads them into the world of heroin addicts, gay clubs, and car-motorcycle chases.