Night Moves (1975)

Synopsis
Private eye Harry Moseby (Gene Hackman) is dedicated to his job, but his dedication does not make him happy or powerful in his personal life, and his wife (Susan Clark) is cheating on him. Aging actress Arlene Iverson (Janet Ward) hires Harry to find her trust-funded daughter Delly (Melanie Griffith), distracting Harry from his marital problems as he tracks the lascivious runaway teen to Florida. In the Keys, Harry has an affair of his own with Paula (Jennifer Warren), and he succeeds in locating Delly, even as he learns that finding her is only the beginning of a much larger case. As the "accidental" deaths multiply, Harry discovers that everyone has his or her own motives and that he cannot do much to stem the tide of deep-seated depravity. ~ Lucia Bozzola, All Movie Guide