Dirty Affair(1990)

Original title: Gumapang Ka sa Lusak

A teenage boy befriends a starlet who is having an affair with an ambitious mayor. As the elections are coming up, the mayor's wife wants him to get rid of his mistress. The starlet agrees to stop the affair on condition that the mayor help release her boyfriend from jail. The mayor does so, but wants the former jail-bird to kill his political rival.