2068 A.D. – Captain Black, an highly-regarded senior agent of the world security organisation, Spectrum, makes an uncanny mistake while conducting a research discovery mission on Mars, trying to evaluate where a set of mysterious signals have been originating from. But while doing so, he mistakes a surveillance device for a defence weapon, when discovering a massively-scaled, futuristic complex, built and controlled by an unknown force, who specifically call themselves ""The Mysterons"".

Unintentionally destroying the peaceful colony, Black is taken over by the hostile power, and from there on, will be the Mysterons' primary instrument to devise their acts of retaliation, swearing upon their declaration that they will annihilate all life on Earth and will unleash a very extensive war of nerves upon the innocent planet.

To make their unveiling statement known, they plan to kill the World President, and in order to accomplish their first attack; the Mysterons cause the car which Captains S

A Mysteron sniper performs an unsuccessful attempt on the forces' new target: The Director General of the United Asian Republic, with Captain Grey arriving in the nick of time, and succeeding in disposing of the eavesdropping gunman. From there on, all personnel from Cloudbase and Spectrum H.Q. – London, along with the recovering Captain Scarlet, and his original partner Captain Blue, are dispatched to protect the Director General at all costs, whom has made arrangements to return to his home country. But the Spectrum officers are completely unaware of the inbound Mysteron-reconstructed civilian Stratojet airliner, the enemies' tool to fix and complete their assassination upon the important international foreign figure.

In the centre of London, the capital of England, a double police-escorted transporter, carrying a nuclear explosive device, built for civilian use, seemingly goes out of control, shaking of its' motor guards and its driver regaining conscience in a back alley. The transporter, now in the remote-controlled possession of the Mysterons, has been hidden in an under construction car park. Captains Scarlet and Blue are assigned to investigate the drivers' mysterious discovery, that the famous Big Ben clock struck 13 times, which may be a clue to finding the transporter, before it destroys the whole of Central London. However, the driver's founding's are more than unreliable due to his perplexed state of memory.

At the Culver Atomic Centre, located in Yorkshire, England, Captain Black accidentally exposes himself to a short-term radioactive isotope, when detected by the security guards, causing his hesitation. Although the isotope is physically harmless, it makes him a straight-forward target when using radiation-tracking systems during Spectrum's full-scale manhunt, to uncover and apprehend the Mysteron agent.

But when the organisation is decoyed, Black manages to kidnap Symphony Angel, who disobeys direct orders from Colonel White. Instead of maintaining her aerial surveillance mission, she finds herself on death-row, in a radiation chamber, and Black in absolute control, with the judgment of killing her, or letting her go free.

The Frost Line Outer Defence Base Network, is endangered by the Mysterons when they destroy a maintenance truck, murdering it's engineer/driver in the process, as a cover to infiltrate the defence bases sited in Northern Canada, where the Mysteronised engineer intends to proceed in removing all oxygen from the bases' self-contained atmosphere.

With bases' ""Red Deer"" and ""Carriboo"" already taken down, the next base in the ring, ""Big Bear"", is the Mysterons' final target, but if the base is attacked also, the commander-in-chief of the defence network plans to commence a vengeful missile strike on Mars, where the main Mysteron complexes are established.

Colonel White desperately wants to prevent this from happening, and so, he assigns Lieutenant Green to his first off-base, ""in-the-field"" assignment, along with Captain Scarlet, to evaluate just how the bases are being cut off, and stop the maintenance engineer from triggering off a global disaster.

When a radio station relay and communications satellite is recreated by the Mysterons and its course altered towards Cloudbase, Colonel White orders the fatal missile to be destroyed before it collides with the aerial base.

Infuriated at his superior for dis-regarding the non-existent, but beknown to Scarlet, lives of the men on-board the satellite, he declines White's proposition to be temporary commander-in-chief of Cloudbase, and therefore, the offer is handed to the honoured Captain Blue.

Leaving for a surreptitious destination, which only White has exposed to Lieutenant Green, and with harsh instructions not to publish it to anyone at all, he arrives on-board the USS Panther II submarine, with the alias Robert Snow, where shortly after one of the ensign officers is, with intent, murdered and reconstructed by the Mysterons in their newest play of vengeance to kill Colonel White.

General J.F. Tiempo, the Commander of the Western Regional World Defence Government, is submitted to the Mysteron's next punishment target, and the doctor who will perform a major and much-required operation on Tiempo is eradicated during a dramatic car crash involving Captain Black, and reconstructed by the Mysterons.

Spectrum are still befuddled on how the force have declared their act of retaliation as to ""kill time"", but Captain Magenta eventually cracks the dilemma and an elaborate game is underway by the Spectrum personnel, in order to trap the person who will take the life of the General, but two advantaging surprises are about to be opened by the Spectrum officers, which will undoubtedly assist them immensely in their contemporary battle with the Mysterons.

But, what they don't realise, is that the doctor who will pefrom the neurosurgery operation on the General is a Mysteron killer.

A divulged, top-secret meeting with the World President and two Spectrum Intelligence Agency officers, one of which is a general, the other a science doctor, who has created a new Mysteron electrical gun & detector following the inexplicable events with the late Doctor Magnus who attempted to kill General Tiempo, takes place in the shooting grounds of an African private game reserve.

Colonel White and Captains Scarlet and Blue find themselves in a treacherous hunting sport, when the Mysterons helplessly attempt to prevent Spectrum from conducting the usage of their two brand new and innovative mobile weapons where one can kill a Mysteronised person with a strong electricity voltage, the other can distinguish and identify Mysteron characteristics within a person using normal X-Ray systems.

But, unbeknown to the group of men, there security officer-in-charge, Captain Indigo, has been murdered in cold-blood by Captain Black.

A modern generation kind of tank, the Unitron – a deadly computer-assisted vehicle, is seized by the Mysterons to destroy the Supreme Commander of the Earth Forces, when he is escorted by Captain Blue to the tanks' testing range field in the Sahara desert.

Two of the Commander's highest-ranking officers, Colonel Storm and Major Brooks, while en route to the SHEF headquarters, are killed in an explosive collision in a mountain-integrated tunnel, involving their car and a gasoline tanker truck, and consequently revived back to life with Mysteronised bodies.

Both men are used as composers to complete the Mysteron's threat, with Major Brooks' attempt becoming unsuccessful, but Colonel Storm's turning into a life-threatening situation when accompanying the Supreme Commander to Point 783, the acting command post where the two test co-ordinators are carrying out final tests with the Unitron, but little do they know that the Mysterons have programmed the mighty formidable weapon to seek and de

The Mysterons present to Spectrum their new act of avenge; to kill one of the Angel pilots, and with Destiny on vacation, she is their apparent target, so Captains Scarlet and Blue fly to Paris to pick her up and accompany her back to Cloudbase.

On the way back, 3 brand new, un-painted Angel Interceptors, reconstructed from those that were subsequently destroyed in a scorching warehouse fire, open fire upon the Spectrum personnel, but a daring dynamic and enthralling aerial dogfight between the Mysteron aircraft and the real Spectrum Angels ensures, testing Melody's Rhapsody's and Harmony's outstanding skills and training to the maximum.

A Variable Geometry Rocket is hi-jacked by a Space Major Reeves, an old accomplice of Colonel White's, who launches the space-plane and makes a quick departure in a fighter jet with the rocket's flight programme unit, which only he knows the 4-letter self-destruct code, to obliterate the rocket before it knocks out an essential target, which happens to be Base Concord, the state-of-the-art airbase where the rocket originally left from.

Captains Scarlet and Blue are assigned to self-destruct the rocket, before it reaches Base Concord, but to accomplish this, they have to check 10,000 possible 4-lettered code-words, starting from 'ABLE', and they don't even know that Reeves has set the destruct code-word as 'ZERO'.

Captains Scarlet and Blue travel to the Himalayas to supervise and administrate Spectrum's new phase to monitor signals from a space satellite that has been launched into the orbit surrounding Mars, and to snap-shot high resolution detailed pictures of the planet, which will be relayed and received by the large mountain satellite station that the probe was launched from.

The second satellite, with the first acting as a decoy, successfully lands on Mars, and sets to have Spectrum successfully completing the code-named ""Project Sword"" operation, but the whole carefully-planned out arrangement is placed under threat when one of the participating technicians ostensibly falls dead and is brought back to life by the Mysterons, with one instruction: to sabotage the observatory and to interrupt the satellites' transmission, before Earth comes to learn every single detail about the force, and prevent them from continuing the war of nerves and retaliation against the planet.

While relaxing at a smart countryside restaurant during a late evening, Captain Blue, accompanied by Captain Scarlet, starts to feel strange after drinking a cup of black coffee.

When Scarlet goes to fetch their coats, Blue instantaneously disappears, and when awakening, finds himself sitting in Lieutenant Green's chair back on Cloudbase, with a Spectrum Intelligence agent, who calls himself Colgan, sitting in Colonel White's chair.

He explains that Blue has been absent without leave for three months, and must prove his identity by disclosing top-security information; the Spectrum cipher codes, before he can return to active duty.

Without having to do this, Captain Blue instead story-tells three Spectrum assignments involving the Mysterons: the nuclear attack on London, the mission of destroying the Mysteron complex in Crater 101, and the prevention of a Mysteronised Commodore and his aid from slaughtering the Supreme Command of the World Air Force at the Scottish Glen Garry