During the Imperial Era, Cassian Andor, a Captain in the rebellion, and the KX-series security droid K-2SO were dispatched on a mission to infiltrate and plunder an Imperial freighter located in the F'tzner system.
Within the confines of the F'tzner system, a raid was executed by Cassian Andor and K-2SO on an Imperial freighter. Stormtroopers were incapacitated and scattered about, the result of Cassian's deployment of poisonous gas to create the illusion of a smugglers attack. Cassian urgently instructed K2 to depart immediately to rendezvous with a Rebel strike team. He emphasized the Rebel Army's need for specific items; however, upon locating them, he was surprised to discover three Wookiee prisoners. Acknowledging the risks of bringing the Wookiees on the upcoming raid, Cassian and K2 opted to leave them on the green moon known as Charissia.
Cassian Andor and K-2SO touched down on the moon's surface with their U-wing. K2 attempted to persuade Cassian to let him participate in the raid instead. Cassian declined, tasking K-2SO with guarding the Wookiees while he proceeded with the raid. Cassian assured K-2SO of his return by sunrise, entrusting the droid with the responsibility of watching over the Wookiees.