Given the extraordinary popularity of Khaled Hosseini’s best-selling 2003 novel and the success of the movie adaptation four years later, it was virtually inevitable that there would be an attempt to create a version for the theatre – despite the fact that epic narratives don’t tend to translate easily to the stage. The book spans three decades and two continents as it enmeshes the story of Afghanistan’s bloody political convulsions (from the Soviet invasion to the rise of the Taliban and beyond) with a personal saga of betrayal, remorse and attempted restitution. Sometimes with challenging material like this, an adaptor can be most faithful to the spirit of the original by taking the piece by the scruff of the neck and using bold, theatrical language to make us see its underlying causal and emotional patterns in a disarming, less realist light. The work of companies such as Shared Experience, Complicite and South Africa’s Isango Ensemble has been exemplary in this respect.

Matthew Spangler, in this American adaptation of The Kite Runner first seen in the UK at Nottingham Playhouse in 2013 and now making its debut in the West End, has a more conservative idea of fidelity than that. I should, though, preface my misgivings about his rather plodding treatment with the acknowledgement that I found the evening very moving. That’s because Hosseini’s story touches in us such primal feelings – anxieties (about the extent of our courage in a crisis), say, or our desperate desires (for a second chance) – that you would have to be made of stone not to be to be deeply affected.

It’s indestructible. And Giles Croft’s production is performed with a sturdy integrity and staged with impressive economy. Barney George’s design is dominated by a massive fan-shaped kite that can be parted like curtains or be a screen for projections or shadow-play, while the requisite atmosphere is conjured by Hanif Khan with his on-stage playing of the tabla and shimmery-sounding bowls. There are a few expressive kites whipped around on shortish leashes but the aerial tournament is mostly evoked through mime as the cast tug on imaginary strings or wave the spindles like miniature wind-machines.

Hosseini has praised this adaptation, saying: “What is appealing is that it lets you put a lot more of the book and text on stage” (as opposed to the film version). But actually it feels top-heavy with relentless first-person narration. The story is recounted by Amir, a thirtysomething Afghan refugee in San Francisco, who takes us back to his Kabul childhood and to the shameful incident that has shaped the rest of his life. The son of a wealthy liberal, Amir was inseparable best friends with Hassan, the son of his father’s Hazara servant and the best kite runner in Kabul. But Amir hid and did nothing to defend Hassan when he was brutally sodomised by Pashtun thugs. There are no child actors in this version. Instead, Ben Turner plays Amir at all stages and is much more successful at portraying the adult, racked still with guilt over a failure of courage that has had such fateful long-term consequences for everyone.