Reeling from a breakup, Eileen enrolls in an intense gym class run by a charismatic but deranged coach. When she quits the program, he abducts her and imprisons her in his sadistic training compound, forcing her — and other captives — through punishing, often lethal workouts. As the physical toll mounts, Eileen must outwit the coach’s vicious regimen and turn his obsession with control and perfection against him before it’s too late.