A manhunt begins for former Spectrum agent Captain Black after a failed break in at a nuclear power plant, where he is accidentally exposed to radiation and becomes detectable for 48 hours.

Following the latest Mysteron threat, Captain Scarlet is dispatched to supervise security at the International Air Conference at Glen Garry Castle in Scotland.

As the Mysterons threaten to destroy the "Heart of New York", Captain Scarlet and Captain Blue investigate the theft of Grade A Security documents from the Spectrum security vaults.

When the Mysterons threaten to kill one of the Angels, Captain Scarlet and Captain Blue are sent to Paris, where Destiny Angel is on holiday, to escort her back to the safety of Cloudbase.

Captain Black engineers the death of chief test pilot Major Gravener, who is retrometabolised as a Mysteron agent as part of the Mysterons' plan to destroy the World Capital, Futura City.

The Mysterons threaten to destroy the Triumvirate of Europe, the three most powerful men on Earth after the World President.

Captain Scarlet and the rest of Spectrum are in a desperate race against time to defeat the Mysteron's latest threat, the total destruction of the massive desalination plant at Najama, high in the Andes Mountains.

After a series of suspicious Spectrum hovercraft crashes, Captain Scarlet and Captain Blue are sent to the Australian Outback investigate if the Mysterons claims that their is a traitor in Spectrum is true.