Four further episodes chronicling Captain Scarlet's battle to save Earth from a Mysteron invasion. In 'Avalanche' Captain Scarlet is called in to investigate when the Outer Space Defence System comes under Mysteron attack. 'White as Snow' sees Colonel White become the victim of a potential Mysteron assassination. 'The Trap' finds Symphony Angel and Captain Scarlet trapped together in a dungeon. And 'Operation Time' has Spectrum protect General Tiempo from Mysteron assassination threats.