The Castell system was a star system located in the Colonies region of the galaxy. The planet orbited within the system, and was in turn orbited by Sienar Fleet Systems Orbital Shipyard CC-24. During the reign of the Galactic Empire, a group of thieves led by the smuggler Lando Calrissian stole Galactic Emperor Sheev Palpatine's personal pleasure yacht, the Imperialis, from CC-24. A trio of Star Destroyers were sent to recover the yacht before it could escape and destroy the shipyard as punishment for allowing the robbery to take place. The Imperials were successful in destroying CC-24, but failed to stop the Imperialis escaping.