The Stepmother (1980)

Langa, a young man trying to make the most of his lot in life, learns that his father is about to marry his pregnant girlfriend. But after the new Stepmother moves in, things soon start to turn for the worse for the young man when the conniving woman, unbeknownst to both Father and Son, starts using muti, a form of traditional medicine, to take control of the household. With the Father completely under her spell, she convinces him to kick young Langa out of the house and onto the streets, all in an evil plan to bring her own son, Sipho, into the fold. With her diabolical plan in motion, she and Sipho manage to kill the Father, but their crime is not a prefect one as a policeman witnesses Sipho fleeing the scene and both Stepmother and son are ultimately brought to justice.