| Timeline for 4920 |
In 4920, the Seventh Doctor, Ace and Hector Thomas visited Titan Base. The TARDIS had been commandeered by Hector, who had fallen under the control of the Swarm. The Swarm ensured its own creation by returning to the Bi-Al Foundation on K4067, where it mutated from the Saturnian plague. (AUDIO: Revenge of the Swarm)