A new drug, HE-11 (also known as "Flash"), has arrived on the streets of Demeter causing spontaneous combustion in its users. While Brogan and Haldane visit Interchem, the pharmaceutical company which originally developed the drug, Orrin and Romek run into trouble when Interchem's chief chemist, Pola Vad Moonacki, is kidnapped.
The Lunar Controller declares the Moon neutral in the "war of nerves" between Earth and Mars. Dispatched to investigate suspicious activity on the satellite's far side, Scarlet, Captain Blue and Lieutenant Green make a shocking discovery.
Mr and Mrs Space Spy issue a fake distress call in an attempt to trick Zodiac into handing over a convict in transport. (Intro special guest: Beth Chalmers)
Harry is the victim of a car crash. But was it an accident?
A message on Sproggle’s radio draws the Paradox crew to the Mountain of Morg on the planet Zark to search for the Lavender Compass that will lead them to Lavender Castle. But the caves of Morg are laced with deadly traps and the travellers' every move is being watched by a sinister figure who wants the Compass for himself.
Strange events befuddle the Alphans as they approach the planet Piri. When exploring its lifeless surface, Koenig encounters the seductive servant of the mysterious Guardian of Piri. She offers the wayward Alphans a life of peace and perfection. Realising the deadly truth behind the peace of Piri, Koenig struggles to free his people from the Guardian's influence.
Father Unwin falls ill from heatstroke and recovers at his vicarage. After reading a newspaper article about an epidemic in Africa, he has a surreal dream in which he and Matthew are tasked with ferrying medical supplies to Bishopsville in a flying Gabriel. When they are captured by native tribesmen for human sacrifice, Unwin must save himself and Matthew with the help of his gobbledygook.
Pedro and Fernando take "Doc" Haggerty and hold him hostage for ransom. (Intro special guest; Nana Visitor)
The Overlander is hijacked, but the hijacker, a news reporter by the name of Darrel, is a potential security hazard for the Terrahawks.
An exploitative businessman is compelled to change his ways after he is bewildered by Joe 90's multitude of brain patterns.
When aircraft are shot down during live broadcasts of a hit song, International Rescue suspects foul play. Tin-Tin and Lady Penelope (posing as the singer Wanda Lamour) investigate, but are left in mortal danger when a ski lift is sabotaged and speeds out of control down a mammoth mountain slide in the Alps.
In Malta, Harry gets involved with an Arkansas millionairess, her pet dog, and a piece of microfilm.
Torchy and Squish go in search of cardboard to repair the rocket, and they discover the Ting-a-Ling bird, who suggests that they dig at the base of a pepper tree. Although the bird's hunch was wrong, Pom-Pom is overjoyed to find a puddle of chocolate.
The Mysterons threaten to obliterate the entire Atlantic Seaboard of North America.
Small-time crooks are turning up dead on the streets of Demeter City and a search begins for the prime suspect Mas Maharg, spotted at the scene of the second murder by Romek's new partner Morgan. Then Fredo's daughter Estes is taken ill and Brogan realises that she has been picking up the killer's thoughts with her paramental eye.
Straker is attracted to a reporter who poses a possible security leak for SHADO.
Captain Scarlet is guarding a particle collider at the Laroux Foundation in Louisiana. When a container tank is hit it releases a gaseous substance with special properties, which the Mysterons use to create an exact copy of Captain Scarlet. After disposing of the real Scarlet, the clone makes his way back to Cloudbase, intent on killing Colonel White. Later, it sets about destroying Skybase and Houston.
Spyros the bandit tries to keep Supercar from discovering his submerged secret.
A medicine man arrives in town claiming to have a cure for everything and almost puts Doc Haggerty out of business before it is discovered where the true source of the medicine comes from.
The new crew of the Paradox intercept an Intergalactic Distress Call and trace it to the Dragon’s Planet where they find a dying old lady in a dilapidated house inside a huge plant pod. She asks them to grant her dying wish, but Captain Thrice discovers a plot laid by Dr. Agon to trap them all inside the pod!
