Drill Sgt. Jim Moore (Jack Webb) is known as one of the toughest in the military, and it's his job to turn boys into Marines. One of the recruits -- Pvt. Owens (Don Dubbins) -- proves problematic, and his incessant complaining and repeated mistakes lead Moore's superior, Capt. Anderson (Lin McCarthy), to issue an ultimatum. Moore has three days to make a Marine out of Owens, or the recruit will be discharged. Moore makes it his mission to help the man fulfill his potential.