The Mysterons threaten to destroy London and a truck carrying an atomic device goes missing and is hidden somewhere in the city. The only clue to its whereabouts is the truck driver, found unconscious in the street.

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.

When the Mysterons threaten to destroy key links in the Frost Line Outer Space Defence System, Captain Scarlet and Lieutenant Green race to investigate the mysterious deaths of the personnel at Red Deer Base.

The Mysterons threaten to kill Colonel White and after their initial attempt fails, White elects to leave Cloudbase so as not to place the other Spectrum agents in jeopardy.

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

The Mysterons' cryptic threat to "kill time" has the Spectrum personnel stumped until Captain Magenta realizes that their target is General Tiempo, the Commander of Western Region World Defence.

Spectrum and the World President attend a secret conference on an African game reserve to demonstrate two new anti-Mysteron gadgets, a Mysteron Detector and a Mysteron Gun but the aliens announce they intend to sabotage the event.

The Mysterons threaten to obliterate the continent of North America, but Spectrum is left without its number one agent when Captain Scarlet is dismissed for gambling offenses.

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 Lunar Controller claims he can negotiate peace between the moon and the Mysterons, Captain Scarlet, Captain Blue and Lieutenant Green are sent to the moon to investigate.

The Mysterons take control of an experimental super-tank in an attempt to assassinate the Supreme Commander of earths armed forces.

Destiny and Symphony Angels go undercover as models when the Mysterons target fashion designer Andre Verdain, who is also the secret controller of the European Area Intelligence Service.

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.

The Mysterons engineer the launch of a Variable Geometry Rocket from Base Concord and their agent, Major Reeves, escapes with the destruct mechanism and target information.

Captain Scarlet, Captain Blue and Lieutenant Green volunteer for a dangerous mission to remove the power source of the Mysteron complex inside Crater 101, on the far side of the Moon, before it is destroyed by a low yield atomic device.

Captain Scarlet and Captain Blue are sent to observe an operation to obtain vital orbital reconnaissance photographs of Mars. But the project is put in danger when one of the astronomers is taken over by The Mysterons.

Using the Mysteron pulsator recovered from the complex in Crater 101, Dr Kurnitz has developed a transmission device with which Colonel White attempts to contact the Mysterons and sue for peace.

When the Mysterons threaten to immobilize the whole of Spectrum, Captain Scarlet and Captain Blue are sent to the Spectrum oil refinery at Bensheba to protect the fuel that powers all of Spectrum's vehicles.

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.

When the Mysterons threaten to sabotage a vital conference at Lake Toma in Switzerland, Scarlet and Blue are assigned to escort the world's leading astrophysicist, Dr. Conrad, to Geneva.

Mysteron agent Judith Chapman, steals a phial of deadly K14 virus - enough to kill ten million people - from Biological Research Station with the intent of poisoning a unknown cities water supply.

Tritonium alloy mining operations at Hotspot Tower in the North Pole are threatened when a Mysteron agent cuts the power to vital heating elements.

A truck carrying an atomic core reactor to the new Manicougan power complex falls into the hands of the Mysterons who intend to use it to strike the Atlantic Seaboard of North America.

When the Mysterons threaten to destroy President Roberts within twelve hours, Captain Scarlet is assigned to guard the skeptical President of the United States.

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 there is a traitor in Spectrum is true.

Spectrum personnel inexplicably take leave of their senses, due to drinking some champagne drugged by the Mysterons, who have threaten to destroy the World Navy Complex at Atlantica.

After the Mysterons threaten Spectrum's Cloudbase headquarters, a large fast-moving trace appears on the radar.