Berlin in the 1920s is a vibrant metropolis. After the horrors of the First World War, people seek their fortune at parties, in glittering variety theaters and dance halls. So-called "ring clubs" dominate the world of crime. When Inspector Paul Lang finds his friend, public prosecutor Barnekow, dead in the crocodile pool of the Tiergarten, the mastermind seems clear, at least to him: the murder clearly bears the signature of Immanuel Tauss, the former head of the gangster ring "The Crocodiles". But Lang's biggest adversary, Tauss, is in prison. Together with his assistant Conrad Ruppert and his secretary, Lang sets about solving the case and encounters the unscrupulous up-and-comer Viktor Parkov and the fascinating vaudeville owner Irma Berger in Berlin's night world. Another corpse opens up a surprising twist, but Lang is already deeply entangled in his personal duel with Tauss - and himself.