Richard Burton plays a psychiatrist who attempts to discover why young Peter Firth has taken to mutilating live horses. In probing Firth's psyche, Burton discovers that the source of the boy's obsession is his mother, Joan Plowright, who has raised Firth with a convoluted set of values. Even as he gets closer to the reason behind Firth's horrendous acts, Burton discovers many previously locked-away secrets within himself. Equus was based on the play by Peter Schaffer who received an Academy Award Nomination for his adapted screenplay.