The US Army has decided to modernize its cavalry, so Colonel James E. Devers is ordered by a general to convert a horse unit to motorcycles, but his men are easily outclassed as riders by a pack of rowdies, especially Grady Westfall; when he is arrested risking a long jail term, he's given one way out: enlisting as Corporal, assigned as driving instructor. Unit commander Captain Jack Hassler reviles his unorthodox boyish methods as undermining discipline and tradition, not to mention flirting with the Colonels daughter Beryl Ann, but he's needed, especially when his unit is deployed on a secret mission in Spain.

"He was born to break the rules."