Dead lagoon

In the highly atmospheric Dead Lagoon, the fourth in Dibdin's series on Aurelio Zen, the detective manages to get himself assigned to Venice, his hometown, in order to engage in some lucrative private sleuthing on behalf of his American former girlfriend. He succeeds in both his official and unofficial enquiries, but not before tangling with a local politician on the make, and a childhood friend - and suffering the shattering of his youthful illusions.