Zerox was a planet inhabited by a humanoid race. When the First Doctor arrived on Zerox, he thought it looked too dangerous for John and Gillian and made them stay in the TARDIS. He was almost immediately captured by natives and taken to their Emperor, who made him fight a beast in the arena. The Doctor fended it off with a sonic beam in his watch and escaped. When the natives hunted for him, he used sleep-inducing arrows and smoke bombs to avoid capture, but was eventually cornered on a cliff. Fortunately, he was rescued by John and Gillian, who used jetpacks to fly in and carry him to safety. (COMIC: The Hunters of Zerox)