The Two Jakes (1990)

Los Angeles 1948: private eye Jake Gittes shall convict the client Jake Berman's wife of adultery. But instead of making her a scene like planned, Berman shoots her lover in affect - or was it murder? Gittes is surprised when he learns that the dead was Berman's companion, who now inherits his share of the company. Of course the police doesn't believe it was affect and suspects Gittes too. The dead lover's widow manages to force Gittes into investigating against his own client... The trace leads back to an old case in Chinatown.