Substation Grimdock, often referred to as Grimdock, was a lunar body, a moon, that served as the home world for the bastaks, a species of crustaceans. The Galactic Empire took control of this moon and, with Sergeant Magernon in charge, transformed the entire surface into a massive prison facility. After the prison reached its capacity, the Empire initiated excavation operations on the moon to create more space for prisoners. However, this digging was halted when the workers stumbled upon a bastak nest, resulting in a deadly encounter where the bastaks killed all of them. Following the Battle of Endor, Substation Grimdock came under the control of the New Republic. After the Battle of Jakku, Magernon received permission to remain in control of the prison. He then freed all prisoners who had shown loyalty to the Empire, and these individuals then reached out to pirates for extraction. The New Republic responded by deploying its fleet to blockade the pirate vessels, preventing them from departing and leading to a tense standoff.