Modern-day Texas Ranger, Cordell Walker's independent crime-solving methods have their roots in the rugged traditions of the Old West. Walker's closest friend is former Ranger, C.D. Parker, who retired after a knee injury, and now owns "C.D.'s," a Country/Western saloon/restaurant. Rookie Ranger, James "Jimmy" Trivette is an ex-football player who bases his crime-solving methods on reason and uses computers and cellular phones. Alex Cahill is the Assistant DA who shares a mutual attraction with Walker, but often disagrees with his unorthodox approach to law enforcement.

Michael Long, an undercover police officer, is shot while investigating a case and left for dead by his assailants. He is rescued by Wilton Knight, a wealthy, dying millionaire and inventor who arranges life-saving surgery, including a new face and a new identity--that of Michael Knight. Michael is then given a special computerized and indestructible car called the Knight Industries Two Thousand (nicknamed KITT), and a mission: apprehend criminals who are beyond the reach of the law. The series depicts Michael's exploits as he and KITT battle the forces of evil on behalf of the Foundation for Law and Government.