Thomas is laconic when people leave him alone, and fast with snappy rejoinders when they don't. Vaughn lends the character a soulful stoicism that brightens only when he's talking to his wife about their child. A narcotics courier with a working moral compass, Thomas is ultimately arrested when, during a shootout, he turns on his violent partners to save the lives of the police.
But once he's locked up in a medium-security prison, the leader of a Mexican cartel kidnaps his pregnant wife (Jennifer Carpenter) and orders him to kill a prisoner in a separate maximum security prison -- so Thomas, a man Zahler showed earlier ripping a car apart with his hands, begins assaulting guards in order to get transferred.
Cell block 99 itself is a cartoonishly grim prison sub-basement with broken glass-strewn floors where prisoners are tortured with electrified belts by a villainous, black-clad warden (Don Johnson). The director's storytelling sensibility recalls gritty, right-wing crime thrillers of the 1970s like Death Wish and Dirty Harry, revenge-driven narratives with high body counts. But Zahler approaches the violence as a horror director, crunching bones, smashing brains and ripping faces from skulls; it's definitely a memorable climax for a lengthy series of conversations.