In writer-director Charles Williams’s Inside, Cosmo Jarvis delivers a flinty performance as Mark Shephard, a prison inmate who becomes a father figure of sorts to his new cellmate, Mel Blight (Vincent Miller). Mark is notorious inmate who, imprisoned for the rape and murder of a child, found religion behind bars and now sermonizes at the prison church about miracles. Spellbound by his cellmate, the teenaged Mel plays the organ, feeling a sense of purpose, if not the spirit, that Mark speaks so rapturously about.

Williams’s prison drama is at once a nervy thriller and intense character study. Also at the center of the film is Warren Murfett (Guy Pearce), who, after Mel becomes his new cellmate, orchestrates a plan to erase his gambling debts if he can get the teenager to kill Mark, who has a sizable bounty on his head. As each man processes their thoughts about sin and redemption, guilt and forgiveness—sometimes through letters they write to their victims—Inside becomes a fascinating examination of how people can (or won’t) change. Mark, Mel, and Warren all seem resigned, and that desperation informs the actors’ lived-in performances.