Felon's dialogue is overheated and some of its plot twists are preposterous, yet it's still white-knuckle tense, and held together by dozens of small, well-observed moments.

The most startling performance comes from Val Kilmer as Wade's hardened cellmate, a man who combines bitterness with wisdom.

Mr. Dorff’s hot-wired portrayal of a prisoner under physical and psychic siege gives Felon its emotional through line as Wade’s attitude metamorphoses from stunned disbelief, to terror, to despair, to fury and finally to hope.

Stephen Dorff's powerhouse perf as an ordinary Joe trapped behind bars with warring ethnic psychopaths propels Felon well ahead of its expose/exploitation brethren while still avoiding the pious learning curves of Frank Darabont's prestige prison dramas.

Kilmer and Dorff, who was also an executive producer, immerse themselves in difficult roles.