Sixty-eight years old; a smoker of Sweet Aftons, a dedicated drinker of Aviateur cocktails, and the owner of a charismatic cat named Turbo, Gerhard Self is a somewhat unconventional private detective. During the war he was a Nazi state prosecutor, and he is still haunted by the memories of his misguided youth. His usual cases involve insurance investigations - such as the case of the ballet dancer who may or may not have deliberately broken his leg in order to claim compensation - and he shares them over games of Doppelkopf with his friends: a chessmaster, an ornithologist and a surgeon. So when Self is summoned by his long-time friend and rival Korten to investigate several incidents of computer-hacking at a chemicals company, he finds himself dealing with an unfamiliar kind of crime, and one that throws up many challenges for the computer-illiterate detective. But in his search for the hacker and his attempts to prevent a hazardous chemical leak, Self stumbles upon something far more sinister. His investigation eventually unearths dark secrets that have been hidden for decades, and forces Self to confront his own demons of guilt, responsibility and loyalty.