On demand: "20 Days in Mariupol"

You could think of it as sound professional judgement. In the opening moments of the documentary 20 Days in Mariupol, director (and AP journalist) Mstyslav Chernov reveals he and his team specifically chose the Ukrainian city of the title as a site of interest in early 2022, reckoning it would be one of the first entry points in the event of any Russian invasion. That decision earned him the inside story of the first days of that invasion: close-up views of tanks moving into position, buildings peppered with rockets and freezing, sobbing children being shepherded into horribly spare concrete bunkers. Yet you could only think of as sound professional judgement were you also to overlook the hellish misfortune of being in this place at this time, putting yourself, alongside many others, at the mercy of a sociopath and his loyal forces. Five minutes in, before the invasion proper has begun, Chernov encounters a local woman sobbing in despair over what seems likely to befall her city; he gently reassures her, telling her to return to her home, where she will be safe; the Russians, he insists, will not be targeting civilians. It's not long thereafter that we learn Russian rockets targeted the very same neighbourhood. While understandably fleeing their homes, other citizens accuse Chernov's cameramen of being "prostitutes", preying on their grief. Even in the 21st century, war photography proves to be ugly work, but perhaps Mariupol needed someone to stick around and show us - not just tell us, as the nightly news does, but vividly, bruisingly show us - how ugly it all got: the fear, the anger, the kids bleeding out onto makeshift operating tables. "Show Putin this," one stricken, furious surgeon yells at the camera, and that, you sense, is why Chernov stuck around as long as he did. To show Putin. And to show the rest of the world what Putin did (and does).

In as much as there is precedent here, it would be 2019's For Sama, about a citizen journalist documenting her experiences under siege in Syria. As in that extraordinary documentary, Western news footage is used to contextualise those tragedies and atrocities the filmmaker alights upon at ground level: here, an elderly woman blown clean across her apartment by an explosion in an adjacent building, say, or a separate rocket attack that removes a teenage footballer of his legs. For Sama (because initiated by a woman?) balanced its despair with more mollifying material: the courage of the medical staff, the growing love between the director and her surgeon husband, the hope they both retained for their young daughter. Chernov - whose murmured narration suggests a man still hiding out lest he be discovered by Putin's troops, or a form of shellshock explained by these images - appears far less inclined to wrap any of his experiences in blankets: the delivery under fire of a newborn baby, a sequence that explicitly parallels some of For Sama's most unforgettable cinema, arrives as cold comfort in the wake of an attack on a maternity hospital, in which we understand many other mothers and infants will have died. Again, so much for not targeting civilians. Already, you will have a sense of how much of this you can personally take: yes, it could be considered a privilege to look away, pause or walk away completely, but in this instance it does seem to me like a privilege you should exercise.

If there is anything in the way of respite, it comes in the way Chernov at least initially seems to be rattling through the titular days: twenty minutes in, and we're already on Day Eight. But then the Russian forces break Ukrainian resistance on the city's outskirts, and we begin to see and feel everything bogging down: wave after wave of airstrikes keeping those left behind firmly in place, no more so than the bodies in the streets and the mass graves on the edge of town. 20 Days of Mariupol may be the definitive cinematic account of what we mean when we say cities fall: the collapse of structures, morale, people. By Day 12, we really do seem to be tumbling deeper and deeper into the abyss where this civilisation used to be; the barbarians are no longer at the gates, but running loose on the streets, and every subsequent cut threatens to throw up, like vomit or bile, something else you don't want to see. By sticking around so, Chernov is showing Putin, and showing us, what the nightly news could not bear to, but he begins himself to seem bellicose and implacable in this task: he's so single-minded in fighting his fight - keeping Ukraine in the mind's eye - that I started to lament the dwindling humanity in this gaze. (It gets beaten out of him and Mariupol alike.) I understand why he's gone to this extreme: he's both having to combat the claims of fake news coming from the Russian state media, and attempting to cut through the platitudes of handwringing Western politicians. Yet the result can seem like one of those instances where the truth is just too much to endure, and perhaps where conventional criticism is rendered pointless: a film of five-star potency, made up of hideous, enraging, one-star images that compel you to flee the room altogether. Forgive me my ambivalence, and my overwhelming reluctance to recommend 20 Days in Mariupol without caution or caveat, but I don't believe I've ever seen a film that at once feels hugely significant and remains close to unwatchable in places.

20 Days in Mariupol is available to rent via Prime Video, Curzon Home Cinema, the BFI Player, YouTube and Dogwoof on Demand.