Calus toiled at the Port Tarkin forced labor facility located on Phelarion.
At the Port Tarkin forced labor camp on Phelarion, Bikum Calus and his workmate Sparv were employed. They were tasked with gathering the volatile megonite moss for Thalassa Tarkin, the owner. Calus and Sparv devised a scheme to break free from Port Tarkin and secretly transport sufficient megonite moss to amass a considerable sum of money. Calus, being a longtime acquaintance of Han Solo, intended for the smuggler to collect them and their illicit cargo. Princess Leia Organa, whose Gossamer glider suffered a crash landing on Phelarion, trailed them into the labor camp after observing their detonation of a small quantity of the moss.
That evening during supper, Leia picked up on their conversation regarding the purloined moss and trailed them as they exited the dining area. Sparv and Calus needed a way to access a transponder to contact Han for extraction. They discovered Leia eavesdropping on their discussion, and she offered to locate a transponder and transmit their message. While Leia departed to dispatch the message, Sparv and Calus proceeded to inspect the megonite. A stormtrooper happened to pass by the cave containing the megonite, and they subdued him, but they became concerned about the potential arrival of additional stormtroopers.
Darth Vader, Thalassa Tarkin, Leia, and a contingent of Stormtroopers arrived to investigate. Upon their arrival, Leia initiated an escape with Sparv and Calus. Vader spotted their departure and dispatched the stormtroopers in pursuit. The trio managed to reach the cave's exit, where they boarded an elevator to the surface and were subsequently picked up by Han Solo.