Knuckledust (2020) on Netflix

Plot summary

Hard Eight is the only person left breathing inside Club Knuckledust, an elite underground fight club where a police task force finds seven levels of the dead: fighters, assassins and hired muscle from around the world. Chief Inspector Katherine Keaton and her officers get ninety minutes with him before a government official arrives to take him into custody. Was Hard Eight the lone survivor of the slaughter, or the man who killed everyone in the building? Lies come from every mouth in the club, and the officers have to work out what really happened there before their time runs out.