Having resigned his commission in the Survey Service rather than face a court martial, John Grimes is now owner and master of Little Sister, a pinnace spacecraft made of modified gold. Formerly the property of the Baroness d'Estang of El Dorado, the ship has come to Grimes in lieu of back pay, and provides him with the opportunity to run his own courier service. Unable to transport anything other than small loads at a time Grimes's first job is to ferry the attractive post-mistress Tamara Haverstock and her mail from the planet Tiralbin to Boggarty. What should be a easy run turns upside down when they encounter the insectoid Shaara. After being taken by force to an uncharted planet Grimes and Haverstock are tortured and publicly humiliated in front of the indigenous population as a show of superior Shaara might. However, things go awry for the Shaara when the pair escape and are mistaken for gods by the planet's resistance army. Grimes must not only defeat the Shaara to save their lives and that of the planet but also complete his contract and get the mail delivered.