Wilsberg is not only a private detective, he also runs a bookshop for antiquarian books in Münster. Both jobs mix very well. He purchases whole libraries if he can, preferably striking bargains by buying the bequest of a recently deceased. He has got a business card which gives his side job away. So if there are any doubts concerning the circumstances of the demise, the relatives are inclined to employ Wilsberg. Other customers appreciate the chance to hire a private detective discreetly by pretending they are just looking for rare books when they visit him. Wilsberg investigates cases all over Münster and its outskirts.