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By Tristan Lejeune

British playwright Peter Shaffer created two of the more enduring theatrical feasts of 1970s, each with a Latin title, a main character-narrator who never leaves the stage, and generous double-helpings of sensory rewards to go with savory philosophical problems.

1979’s Amadeus floods the stage with Mozart in between fascinating discussions about talent, envy, and God’s place for us in the world.

Equus, which debuted in 1973, is far more primal, and sexual. It has more blood and earth under its fingernails, but just many serious, existential questions rattling around in its troubled head. The fabulous production directed by Amber McGinnis Jackson that the Constellation Theatre Company has going now until Valentine’s Day is full-body entertainment: a delight for the eye, the ear, the mind, and the gut.

Disturbed English youth Alan Strang (actor Ross Destiche doesn’t look 17, but hey, who does?) is on the verge of a life sentence for what the production notes succinctly call “an unspeakable act of violence,” but he is given a fortunate reprieve in the form of a psychiatric stay. Arguably less lucky is his new children’s therapist, Dr. Martin Dysart (Michael Kramer) who now has the daunting task of figuring out why, precisely, late one night this otherwise unremarkable young man gouged out the eyes of six horses.

Shaffer’s script instructs that Strang and Dysart face off for their sessions in a square, but the Constellation’s black box on 14th Street insists instead on a thrust/in-the-round hybrid, and designer A.J. Guban’s set and lights are up to the temporal task. Hollow enough to reverberate, solid enough to stampede upon, the beams and blanched birch-style platforms could be a set for The Crucible with zero changes.

Costume designer Erik Teague knows that he must reside on the unobtrusive part of this particular production — we should be relishing the lights and sound instead, and indeed we do — especially with a house so intimate the audience can make out the herringbone pattern of Dysart’s two-piece, a class act in understatement.

While we’re on the crew, a tip of the bowler to dialect coach Elizabeth van der Berg, who keeps a stage full of Yanks veddy clear on which side of the Pond they find themselves, and with variation. Horseman Ryan Tumulty (who also exudes equine power as the steed Nugget) comes with a haughty drawl that is nothing like Emily Kester’s flirty tones as Jill Mason, except in their authenticity.

And speaking of authenticity, Michael Tolaydo and Laureen E. Smith are so heartbreakingly real as Alan Strang’s parents it’s enough to take your breath away. She’s religious, he’s a socialist, both are well-spoken, and neither has the slightest clue why their baby boy would slash and maim the animals he clearly loves more than anything in the world. They still care about their son, of course, but his crime has created an unbridgeable chasm. Smith and Tolaydo look like they just wandered in from the back room of a village store, keeping calm and carrying on.

The ensemble’s efforts as half a dozen English thoroughbreds are immeasurable. Quite the stable of actors. That everything feels so vital and alive is in no small part thanks to them.

All that and more for composer and sound design Palmer Hefferan, who brings everything from moody echo to Wagnerian fury to the table. The music is haunting and the sound effects transporting; when Equus is at a full gallop, it’s a chest-stirring thrill.

Those of us who caught Daniel Radcliffe’s famously full-frontal production in London in 2007 walked out chattering not about Harry Potter’s wand, but the late Richard Griffiths’s (Uncle Vernon) staggering performance as Dysart, a frightened modern-day witch doctor in an ugly sweater.

Kramer is tweedier and more spry. He stumbled once or twice on opening night among Dysart’s many ponderous monologues (most of Equus is him talking), but the arc of the show is his, and he does not strain to carry it. “What use is grief to a horse?” he ponders in the opening scene. It’s a little thing, but it’s always nice when actors look like they’re smoking because they want to smoke, as Kramer does, and not because they want something do with their hands.

Dysart fears that he neuters the souls of many of the children he heals: exorcising some rich, primitive demon, and Kramer shows flashes of doubt and passion that keep you guessing well into the second act. This play feels much shorter than it is, but it wouldn’t if he weren’t so much fun to watch.

Children before grownups is one of the show’s admirable goals, so Kramer and Destiche set to work on trying to both take Alan’s pain away and figure out what made him explode. For all the lightning and thunder, their duets are some of the best moments.

Let the record show that Destiche’s Strang is indeed better than Radcliffe’s. He doesn’t so much stare as point his whole face at someone, with a constant churning behind his eyes. Of particular fun are the scenes where Strang’s Freudian wanderings take Destiche back to childhood; you can see years of trauma drift off of him as the seeds of worship are planted in heart and mind.

Worship is one many deep themes explored in the (somewhat dated) psychological probes, and the alchemy recipe that Shaffer set down and McGinnis Jackson cooks up is mesmerizing. Equus is the kind of theatre that seeks to raise ancient gods and forge new ones, and it casts one helluva spell.

The gods of theatre — it is certain — are pleased with this offering.