On demand: "Last Breath"

Last Breath is a documentary account of a near-fatal industrial accident; it should by rights be preceded by one of those ads for some "where there's a blame, there's a claim" ambulance chaser. The incident in question occurred in September 2012, when Chris Lemons, one of a three-man team of divers carrying out routine maintenance on a North Sea oil well found himself - via a freak set of circumstances - stranded at the bottom of the ocean, with the umbilical cord connecting him to his diving vessel irreparably severed, leaving him with but five minutes of air, and thus five minutes of life. The directors, Richard da Costa and Alex Parkinson, have given this tale a broadly conventional retelling; they know they've been handed a heartstopping, life-or-death story, and so simply crack on with the job of conveying it. In one respect, they tamp down any suspense by having all three divers - Lemons, Dave Yuasa and Duncan Allcock - appear on screen, very much alive, within the opening fifteen minutes to start their testimony. Thereafter, it's just a matter of whether da Costa and Parkinson can evoke the fear and dread of Lemons' fraught moment under the sea.

They're helped considerably in this task by the divers' own coverage. The specialised sub-aquatic plumbing Lemons undertakes is a complicated process that necessitates a camera being attached to diving masks, and constant monitoring from above; pulled from the deep, Lemons and co. provide a running commentary in talking-head form, and judicious reconstructions fill in any remaining gaps. There's a certain fascination in seeing how this job would be done even on regular, uneventful shifts: da Costa and Parkinson show us the flooding of the diving chamber with helium that gives these roughnecks Betty Boop voices, Allcock's hoarding of chocolate bars for energy purposes, the radar technology that keeps boats faced with rolling tides in more or less the same position, so divers have the best possible chance of returning safely to the surface. The narrative grist, however, is how from the lowest of low points - separated from his vessel and his colleagues, all but written off as dead - this one diver got back to a ship that had drifted several miles away from the dive site.

It was a smart choice on the directors' part to have Lemons go quiet once he's cut adrift, as it suddenly allows the film to repressurise with suspense: we're left wondering where he went, and what he was feeling. What bubbles up in the meantime is a remarkable story of teamwork: how the extraordinarily fleet-footed actions of a group of individuals bound by a deep responsibility to one of their own saved another man's life. Throughout, there's a marked contrast between the gravity of the situation under discussion and the divers' unflustered responses, which you realise might well make the difference between life and death in situations such as these. Time and again, what strikes us as medal-worthy heroism is downplayed and shrugged off as just doing a job, although the deadpan Yuasa is onto something about the nature of his colleagues when he confesses "you don't want to be down there with a knob". (I'll say.) If Last Breath's title sets us to panic stations, then, its content proves unexpectedly buoying: if Chris Lemons can come back from this, there's absolutely no reason why - with the right people around you - you can't bounce back from that ghosting, that bad day in the office, or any other deep, dark place you happen to find yourself in.

Last Breath is now streaming on Netflix.