Roman Coleman has been incarcerated for 12 years after leaving his domestic partner permanently brain damaged in an attack. Aware of his short temper and violent tendencies, he has resisted efforts to be reintegrated back into society. While working outdoor maintenance, Roman is placed in a rehabilitation program run by rancher Myles that assigns prisoners with training wild mustangs. Each prisoner in the program is given a specific horse to train and Roman is required to complete the training within 12 weeks before his horse is sold at an auction.
Roman initially struggles with the training of his mustang, but under the guidance of Henry, an inmate regarded as the top horse trainer, he begins to make progress. As the weeks pass, Roman becomes close with the horse, whom he names Marquis, and forms a friendship with Henry. The program suffers a blow, however, when Henry is murdered by Dan, Roman’s cellmate. Roman retaliates by strangling Dan into unconsciousness before they are broken up by guards.
The day of the auction arrives, which Roman invites his pregnant daughter Martha to attend with the hope of improving his relationship with her. While Roman showcases Marquis to the auctioneers, he becomes distracted after he notices Martha is not present. This distraction leads to disaster when Marquis is startled by an overhead helicopter, causing Roman to fall off his horse and nearly be trampled as the other trainers restrain Marquis. Shortly afterwards, Roman learns from Myles that Marquis has been deemed untrainable and will be euthanized. Taking advantage of the prison gates being damaged by a storm, Roman is able to help Marquis escape.