Pink Mist (Bush Theatre)

Pink mist – picture it. The phrase conjures a peaceful, tropical landscape: rainforests at sunrise, hillsides on the subcontinent. In fact, it's a beautiful term for an appalling thing: military slang for a body, vaporised in battle; blood hanging in the air like liquid gas. Pink mist. "When one of your mates hasn't just bought it, but goes in a flash," says one of the squaddies Owen Sheers puts on stage. "From being there to not."

All the way through Sheers' spoken word play, you tune into the language of war afresh. All that shorthand and slang becomes see-through: a way of tiptoeing around the truth, dressing up the realities of war in pretty idioms and metaphor. You hear the implications beneath "a nest of Taliban," and the FUBAR that is "friendly fire." You realise why everyone gets a nickname, what it takes to communicate with locals, how laced our lives are with images of war. One solider on R&R flips at the shot menu of a local night club: Jäger bombs, Berry bombs, Fireballs.

Sheers signs us up with three young Bristolians, fresh out of school with few available options. They go from playing war in the playground to waging it for real in Afghanistan; six weeks basic training then service. Arthur (Phil Dunster, first class) is drawn to the uniform – a desire to stand tall – but, for his best mates Taff and Hads (Peter Edwards and Alex Stedman), it's the best career path that's open. No-one signs up, if there's a decent job going elsewhere. "Not going someplace," says Arthur, "but leaving somewhere."

It's a play that gets right into the psychology and the physicality of squaddie life – and George Mann and John Retallack find a regimented choreography of precise gestures, not unlike military sign language. Sheers has spent a lot of time with ex-soldiers (he wrote The Two Worlds of Charlie F), and it shows. He finds details others don't: the smell of explosives, the dark of a desert, Camp Bastion's very own Pizza Hut. His writing has the authenticity of a verbatim piece, without the flatness of testimony. Unlike other writers, he accepts the dignity of war, as well as its tragedy – and, while that can lead to bombast, it pays off in power and complexity.

The tragedy, he suggests, goes largely unseen – at least, it doesn't show up in news reports and casualty lists. War doesn't just take lives, it ruins them too, robbing men of limbs and sanity, families of normal family life. Though slightly tacked on, Sheers gives voice to the women back in Bristol – mothers, wives and girlfriends – waiting to pick up the pieces.

As a writer, Sheers places contemporary conflicts into the tradition of war poetry: Homer, Wilfred Owen, Siegfried Sassoon – that sort of thing. On the one hand, that lifts images of war out of the news media and into inverted commas. Desert camos and IEDs have become part of life. Sheers repositions them as part of death. On the other, it means Sheers tends to replicate old tropes. Three boys leave Bristol, only one and a half – max – come back. Dramatically, you know exactly where Pink Mist is heading, but it also tips the scales too far. Soldiering's not safe by any means, but it's not the life or death sentence Pink Mist makes out. By falling in line with old war stories, Sheers misses the opportunity to find others: the perspective of female soldiers, contented professionals and Afghan life are all conspicuously absent.

Pink Mist runs at the Bush Theatre until 13 February, then at Bristol Old Vic from 16 February to 5 March.