Shackles (2005)

Ben Cross (D.L. Hughley) is desperate for work when he's contacted by a warden (Georg Stanford Brown) to teach at his prison. Cross jumps at the chance, hoping to inspire inmates with the power of words, but he meets resistance. Through sheer force of will, he manages to get his message across -- especially to Gabriel Garcia (Jose Pablo Cantillo), who excels under his guidance. Some prisoners are harder to reach than others, however, and Cross faces a situation that threatens to explode.