Why would a teenage boy who works with horses blind several of them with a hoof pick? Based on real events, that’s the question posed by Peter Shaffer’s 1973 neoclassical drama, which, like the Greek tragedies that inspired it, is part case study, part horror story. This dazzling revival puts across its answers as well as could be imagined. Zubin Varla is terrific as the psychologist investigating, a cold man who doubts his calling. As the unstable stable boy, Ethan Kai is suitably wild, with the mien of a Caravaggio pagan. For the horses, we get expressive movement from muscly actors. Believe it or not, it works. What I didn’t quite believe in was Shaffer’s central dilemma, which must have seemed trendy in the 1970s — whether we want to be the crazy, ignorant, liberated kid or the controlled doctor.