The series is set in the distant future. Humans have spread beyond living on Earth and have colonized planets across the universe, creating a New Frontier of man. In order to protect these new settlers and maintain law and order in the New Frontier,Earth's Cavalry Command was created. Cavalry Command is a military organization that maintains an army and fleet of ships to protect the New Frontier and the residents of the planets within it known as Settlers. Within Cavalry Command is a unit of special operatives known as Star Sheriffs that function as the organization's field agents, investigating any crimes and plots that threaten the security of the New Frontier.

The main foe of Cavalry Command and the Star Sheriffs is a race of non-human creatures known as Vapor Beings (also sometimes called Outriders) that have jumped into our dimension in order to conquer it. They attack the Settlers, destroy settlements, and kidnap humans in order to mine various metals or crystals from the soil of various planets.

Outriders are superior to humans in battle technology. They control a legion of gigantic robots with weapons greatly superior to the weapons and defenses of the space-going fleets of Cavalry Command. In response to the Outriders' threat, Cavalry Command develops a prototype spaceship known as the "Ramrod Equalizer Unit" (or simply just Ramrod) that has the ability to transform from a spaceship into a powerful robot that can fight the Outriders on equal terms.