Shadow and light - Jonathan Rabb

Berlin 1927: when an executive at the newly-famous Ufa film studios is found dead in his bath, it falls to Chief Inspector Nikolai Hoffner, of the Kriminalpolizei to investigate.
With the help of the German film director Fritz Lang and the head of the most powerful crime syndicate, Hoffner finds his case reaches deep into Berlin's sex and drug trade, and into the political world of Hitler's Brownshirts (the SA).
Caught up in this story is Hoffner's new lover, and his two sons, one of whom works for Joseph Goebbels. We last met Hoffner in Rosa (2007); his relationship with his sons develops menacingly in Shadow and Light.