Ben Cartwright (Lorne Greene) and his three sons, sensible Adam (Pernell Roberts), king-sized Hoss (Dan Blocker), and brash Little Joe (Michael Landon), own the Ponderosa, the largest ranch in Nevada.
When three Union Army soldiers, Tyler (Grant Williams), Sutton (Joe Maross) and Mertz (James Parnell), desert their unit, they attempt to hide out on the vast Ponderosa. After the men viciously attack Little Joe, the Cartwrights are provoked into joining a military posse led by the cruel and sadistic Captain Bolton (Chris Alcaide).