Prisoner Zero is an Australian animated children's sci-fi, action-adventure series produced by Planet 55 Studios. Planet 55 Studios was in reality part of the Big Finish group of companies. Many of the actors involved in the audio drama released by Big Finish Productions Limited had agreed through their contracts for release of their work on compact disc, yet not in digital download format, which required an additional fee to be paid to them all. Prisoner Zero follows the adventures of Tag, Gem, and Del and their mysterious friend Prisoner Zero. These four friends have a mission to free those enslaved across the cosmos from the evil Imperium, led by General Vykar.