What if a man-made virus with the power to melt all plastic became as infectious as the common cold? When a plane crashes in South America, in quite extraordinary circumstances, it's up to Dr Quist's team to avert further disaster.

Doctor Quist and Doomwatch become embroiled in an inquiry into the heart-transplanting practices of Doctor Patrick. Several uncomfortable questions are raised: what has he been doing to a newborn baby that has been placed in his care, and should genetic engineering be permitted in society?

When a lifeboat crew discovers a luxury cruiser adrift in the English Channel, they find on board are a group of wealthy pop stars and their girlfriends, one of whom is dead. Doomwatch investigate, and discover that the death was not from drug abuse as was previously suspected; instead they begin to uncover the facts behind the dumping of a deadly chemical warfare compound in a deep sea trench, which seems to be far from dormant.

Genetic engineering? Tampering with nature in a quest to make Superman? The experimentation is still only being carried out on rats, but with dangerous, and deadly results...

Doomwatch are joined by Doctor Robson, sent to undertake tests on the new 'Sahara' spray which is apparently capable of destroying all plant-life on the planet. But when Quist receives a phone call from the ministry, he is given orders to immediately suspend both Robson and Toby without any explanation. Closer investigation leads Quist and his team to discover that a new computerised security system run by Commander Keeping and Barker has become far too powerful, and is making its own decisions about government personnel.

The first nuclear-powered rocket, Sunfire One, is sent into space with the first British astronaut, Dick Larch, on board. After the rocket enters Earth orbit, Larch enters an incorrect course alteration, and fails to see the error indicator, which results in Sunfire One splashing down in the sea. Quist is asked by Doctor Goldsworthy to determine whether Larch is suitable for any further missions, as another such mistake could result in the spacecraft becoming a nuclear bomb.

While on the way to work, secretary Pat Hunnisett takes a free promotional chocolate from a group of girls on the street. Meanwhile, at the Doomwatch office, Quist and his team are investigating the sudden increase in the country's smokers, and are surprised when Pat arrives and lights up a cigarette for the first time in five years. Quist suspects that there could be a link between the promotional chocolates and 'Checker Board' cigarettes, whose recent sales are doing unexpectedly well. Should subliminal advertising be allowed?

Dr Quist attempts to go on holiday, but gets involved instead in a series of jet engine experiments causing harm and the same mysterious hallucination.

In order to decide on new proposals for dealing with the dangers of pollution on the environment, Doctor Quist assembles a conference amongst the world's top scientists. But soon several of the delegates become ill, apparently from food-poisoning. However, Quist becomes suspicious, and suspects that the sickness may have been caused deliberately.

Two thousand animals are found dead in the Somerset countryside. Doomwatch investigate whether or not a new pesticide is to blame.

The Doomwatch team look into serious health issues experienced by male workers at a Welsh battery farm.

A military plane ditches into the sea whilst carrying three nuclear weapons on board. While the RAF mounts a search mission, an unidentified object is washed up on the shore near Byfield pier on the south coast of England. It is found by two men, Geoff Harker and Sam Billings, who decide that it must be a weather detecting device, and so begin to strip it down for parts. Toby is sent to investigate the device, but he soon finds himself faced with the terrifying prospect of disarming a very live bomb.