Vita Nuova by Magdalen Nabb
When Marshal Guarnaccia is called upon to investigate the murder of a young woman he is convinced that there's more to the family than meets the eye, and wonders if the girl's father, Paoletti, might have had something to do with her death.
Enlisting the help of a local journalist, Marshal Guarnaccia's investigations draw him into the seedy underworld of Florence - lap dancing, prostitution and the illegal human trafficking of Eastern European women who are sold into the sex trade. But can he save these women before it's too late, and what do they have to do with the killing of Daniela Paoletti? Distracted by the plight of these women and the murder investigation, Guarnaccia forgets about his own personal problems; but it's not long before he has choices to make - should he seek help and risk exposing himself and possibly losing his job, or should he go it alone?