P.J. (1968)

Reluctant New York City private eye P.J. Detweiler is hired as a bodyguard to protect Maureen Preble, the mistress of shady millionaire William Orbison. In truth, Orbison plans a deadly intrigue in which P.J. is to play a central part. Meanwhile, complications ensue as P.J. gradually falls in love with Maureen. (Wikipedia)