Rocco Mattarella, a successful restauranteur, has been shot dead in his own restaurant. Prof. Dr. Lisa Wolter reconstructs the crime. Apparently the victim was killed by nine shots, all fired from close range. Joachim Stoll immediately suspects this could be a warning from the Mafia, intended to frighten other restaurant-owners. When Jan Arnaud discovers that nothing is missing from the cash desk, and a threatening letter addressed to the victim comes to light, demanding protection money, it looks as though Joachim’s theory could well be correct. It now emerges that other landlords in the neighborhood have been subjected to pressure: Jean Krause, who runs the Lobby 0711 bar, shows Joachim Stoll a threatening letter he claims to have received just a couple of days earlier.