Equus was first produced in 1973 while the National Theatre company was based at the Old Vic Theatre.
A psychiatrist, Dysart, investigates the case of a disturbed young man who has blinded six horses. In discovering the boy's problems Dysart confronts his own self doubts, and the play questions the value of a psychiatric cure in which intellect destroys passion. The production, directed by John Dexter, was intensely theatrical. A section of the audience sat at the rear of the stage, close to the action, which took place in an area likened to a boxing ring or a bull fight arena. Actors remained on stage, becoming witnesses to events as well as participants. Stylised metal masks and hooves turned actors into terrifying horses.
Shaffer created a memorable central role for the tormented psychiatrist, played in London by Alec McCowen and on Broadway by Anthony Hopkins and Richard Burton.