A striking and violent image dominates the imagination of the audience in this complex and disturbing play: six horses have been wilfully blinded with steel spikes. Why would anyone commit such a brutal act? This deceptively simple question sits at the heart of Peter Shaffer’s Equus, first produced in 1973 at the National Theatre and based on a true story.

Directed by Ned Bennett, this touring revival (presented by English Touring Theatre and Theatre Royal Stratford East) brilliantly evokes both revulsion and fascination in exploring the complexities of 17-year-old Alan Strang’s shocking crime. It’s compelling theatre and a stunning realisation of the play which firmly establishes it as a classic of the modern stage.

Psychiatrist Martin Dysart (Zubin Varla) is tasked with understanding the motives behind the teenager’s violent act after a magistrate friend persuades him to take on the case. As Dysart goads and encourages Alan (Ethan Kai) to speak about his past we are drawn into an uncomfortable world of worship and mutilation, passion and trauma.

As possible motives slowly take shape the play forces its audience to reflect on profound and unsettling questions. Is seeking to understand violent crime tantamount to condoning it? What is the role of psychiatry in ‘curing’ people of their ‘demented’ passions? Does scientific rationality provide a better route to fulfilment in life? What morbid fascination attracts us to people, like Alan, who shun rationality and embrace their passions? Should the criminal justice system punish or treat offenders and how is this different when the offender is a young person?

The writing and characterisation in Shaffer’s deeply affecting and powerful psychological drama are nuanced and full of ambiguity, never providing easy answers to the many and varied questions it asks. A gift for actors and audiences alike.

Zubin Varla’s Martin Dysart is a revelation. His understated manner allows the writing to float and beat freely: it’s a poetic and devastating performance. His reflections on psychiatry (“I stand in the dark with a pick in my hand, striking at heads”) and Strang’s rehabilitation (“I’ll take away his field of Ha Ha, and give him Normal places for his ecstasy – multi-lane highways driven through the guts of cities, extinguishing Place altogether, even the idea of place!”) resonate powerfully though the decades since this ground breaking play was written.

Ethan Kai gives a mesmerising performance as the troubled teenager Alan Strang, lending a dangerous and unpredictable intensity to the central relationship between patient and doctor. His haunting stare is brilliantly unsettling and complex.

The decision not to use model horse heads, costuming or puppets is a master stroke, allowing the audience to enter Alan’s fantasy world more freely. Movement Director Shelley Maxwell’s sinewy and snorting horses, recreated by several cast members, are powerfully alive in our imaginations. Ira Mandela Siobhand’s performance as Nugget, the horse Alan becomes fixated on, is transfixing as he flexes and convulses, somehow capturing the raw power and wild nature of the God-like Equus.

There is excellent support from the whole company, notably Syreeta Kumar and Robert Fitch as Alan’s parents who struggle to connect with a son guilty of perpetrating such a violent crime. This revival is visually stunning too; the billowing white sheets in Georgia Lowe’s design creating both a rational, clinical sterility and the suggestion of a world transcending time and place beyond the confines of a hospital setting.

Equus is a compelling piece of drama and a fascinating insight into some of the darker recesses of the human psyche. It speaks to all of us, whether we like it or not. This beautifully realised revival does justice to the genius of Shaffer’s writing. A must-see.

Equus is on tour with English Touring Theatre until 11 May 2019