THE DOCTOR IS GIVEN AN ASSIGNMENT BY THE Time Lords – he must deliver a sealed despatch box to an unknown recipient on Skybase One, an Earth Empire space station orbiting planet Solos in the 30th century. Accompanied by Jo Grant, the Doctor arrives during a conference with representatives of the Solonian people, where an Administrator from Earth Central is to announce independence for Solos. The Marshal, the station commander, refuses to relinquish his power and arranges for the Administrator to be assassinated during the conference. He frames native leader Ky, an outspoken critic of the Empire’s Overlords, for the murder. As Ky makes his escape, the Doctor realises the despatch box is intended for the rebellious Solonian.