The Virtor were a race of slavers that abducted human students from Earth in 1982 and transported them through time to their home planet of Virtus. Their plan was ultimately foiled by the Second Doctor who, after being transported to Virtus for a long period of time, led a revolution among the slaves against their rulers and eventually returned the students, now much older, to Earth. Only a few seconds had passed in Earth time. (PROSE: The Lost)