It's 1875 Texas and bands of renegade outlaws are pillaging towns, murdering townsfolk and stealing their cattle that they then sell across the border in Mexico. Accordingly, the governor of Texas orders the former state lawmen, the Texas Rangers, re-commissioned and wants their former leader and local preacher, Leander McNelly (DYLAN McDERMOTT), to head them up once more to take care of this problem.
Having lost his family to the bandits and dying of consumption, Leander is hesitant, but eventually agrees, and begins assembling, with his assistants Sergeant John Armstrong (ROBERT PATRICK) and Frank Bones (RANDY TRAVIS), a new group of lawmen. Among them are Lincoln Rogers Dunnison (JAMES VAN DER BEEK) and George Durham (ASHTON KUTCHER), both of whom are now orphans due to the work of the outlaws, as well as Scipio (USHER RAYMOND), a freed slave who wants to prove he's better as a rifleman than as a scout.
As the group sets out to find the outlaws and their leader, John King Fisher (ALFRED MOLINA), they have various encounters with small bands of bandits, and eventually rescue Perdita (LEONOR VARELA), a Mexican circus acrobat from their grasp. Needing to regroup at the estate of Leander's friend, Richard Dukes (TOM SKERRITT), Lincoln and George become enamored with his pretty and high-minded daughter, Caroline (RACHEL LEIGH COOK).
From that point on, the Texas Rangers must overcome long odds, deception and various perilous encounters as they try to find and stop both Fisher and his men.