The show is set in the future, some time after the year 2086, when two aliens from the planets Andor and Kirwin travel to Earth to search for allies against the expansionist Crown Empire led by the Queen of the Crown. In return for the help, the two aliens gave mankind construction plans for a hyperdrive device. After this key event in human history, interstellar travel flourished and a huge number of colonies emerged in distant star-systems. Alongside the growth of human activities in space, criminal activities also grew, and the new colonies required defense against various threats, including the Crown Empire. A group known as "BETA" (Bureau for Extra-Terrestrial Affairs) was founded to cope with these tasks, with a "Ranger" division being a part of it.
Most of the colonies portrayed in the show specialized in either agriculture or mining "star stones". Many of the planets on the show have names that evoke ideas of a Western setting, Nebraska, Mesa, Ozark, and Prairiebeing a few.
BETA is shown to be the major military and exploratory arm of Earth. The organization's headquarters are on Earth. BETA sustains several bases on and around Earth, such as the Longshot Research Facility in the Grand Canyon and the BETA space station in Earth's orbit.
The Series-5 Brain Implant, or S5 is implied to be the closest mankind will ever get to merging with cybernetics. The S5 implant enables a dramatic boost of innate abilities due to its unique conversion of bio-electrical power generated by alpha radiation stored within the badges worn by the Galaxy Rangers.
The Crown Empire, also known as the "Crown," is ruled by the Queen of the Crown, whose intentions and motivations are described as being evil. She controls a large number of planets in a vast section of the galaxy, all of which she rules as a cruel tyrant. The Queen controls her empire using creatures called Slaver Lords with whom she has a psychic link. Slaver Lords derive their power from the psychic energy of other beings. After the Empire encountered humans, the Queen discovered that they were more suitable for energy extraction than any other previously encountered species.