"Outlaw Star" opens on the backwater planet Sentinel III, on which the protagonist Gene Starwind and his 11-year-old business associate James "Jim" Hawking run a small jack-of-all-trades business. After the two take a job as bodyguards for a disguised Hilda and engage in a brief skirmish with the Kei Pirates, Gene and Jim find themselves the owners of the XGP15A-II (which they nickname the "Outlaw Star") and the caretakers of Melfina, though Hilda is killed in the process. Hilda reveals that the ship's true purpose is to locate the , a place which popular claims say is a holder of immense treasure, knowledge, and power. Throughout the course of the series, the crew grows to include the kimono-garbed contract killer "Twilight" Suzuka and the Ctarl-Ctarl alien catgirl Aisha Clanclan.