Self's Punishment - Bernhard Schlink

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 an unconventional private detective.

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 that throws up many challenges. But in his search for the hacker, 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.