The TARDIS makes a emergency landing on Varos, a planet that used to be a penal colony, where the native Varosians are entertained by broadcasts of violence and death. Where the Doctor and Peri are mistaken for rebels, and they learn Sil, the evil delegate of the Galatron mining corporation bids to rule Varos and to control supplies of Zeiton 7 ore, which is the TARDIS's only fuel source.