Stop the presses: we may have just found the cinematic performance of the year. James Cosmo holds all attention front and centre of the ring in this striking, deeply emotional monologue-driven drama about a veteran boxer and his regrets.

Cosmo plays Ray, a world-weary fighter who slowly makes his way into an empty gym and eventually the “square ring,” setting up a video camera to record his thoughts to an initially unclear audience-of-one (although he’s really talking to us). He then proceeds with his 90-plus minute monologue in which he bears his emotional scars and pours his heart out about his love of boxing and regrets over his troubled relationship with his son.

It’s very difficult to make a film set entirely one location, never mind with just one actor relaying a continuous monologue, not just interesting but compelling. And yet somehow directing team The Shammasian Brothers (Ludwig and Paul, making their mightily impressive feature length debut here) and screenwriter Geoff Thompson (adapting from his own critically acclaimed stage play) do exactly that. They mould a gripping, rich, multi-layered slice of drama that works wholly as a cinematic experience as opposed to being a pointless exercise in merely “filming a play,” utilizing stark black-and-white cinematography to give it that timeless quality.

We rarely leave the ring throughout the film – except for fleeting moments of flashbacks to his son (played by Cosmo’s real-life son Ethan) to accompany certain points Ray is making – and we only really have one actor to grasp our attention. And grasp it he does, with both hands and never lets go. In the hands of a lesser actor this whole thing might have seemed repetitive or worst of all uninvolving. But Cosmo gives a truly phenomenal, unforgettable, tour-de-force performance that has you hanging on his every word.

Whether he’s explaining what makes boxing more than just guys knocking lumps out of one another – awash with details that should ring true to any boxers and fans of the sport – or expressing his regrets over his deeply loved but regrettably estranged son, Cosmo keeps you captivated. A final 10 minute close-up of his face which sees this brooding, hulking, manliest of men – who not an hour previous emphatically stated that “we don’t cry in this family” – break down into agonising tears is among some of the strongest, most heart-breaking cinema this year has had to offer thus far. And those waves of emotions are only compounded by a sort-of twist reveal in the narrative that dodges gimmick and lands a strong emotional punch to the gut.

Whilst the monologue that makes up The Pyramid Texts may not be entirely original in its content, with themes of loss and regret being all too familiar, it’s done with such passion, emotion and strength of character that it hardly matters. Nor is it anywhere near strong enough to detract from Cosmo’s career best performance, one that, in tandem with the well-written script and confident direction, makes for a supremely moving, powerful, attention-grabbing piece of British cinema.