John Ridge apparently suffers a breakdown from the pressure, and decides that, due to the excessive threat of pollution on the environment, drastic steps should be taken. He steals some phials of the deadly virus anthrax and holds the government to ransom: unless his anti-pollution terms are met, he will destroy humanity by releasing the virus in a number of major cities. A race against time begins. Can Ridge be tracked down before it is too late?

An inquiry into Doomwatch is begun following the events surrounding Ridge's breakdown. Meanwhile, Quist is summoned to a large country estate in Scotland, where he finds himself offered a new position with both power and wealth in the private sector, but only if he will curtail his investigations into a new drug called disocyanate. Back in London, the Minister decides that it is time to place his own man within Doomwatch, and so despatches Commander Neil Stafford to join the team.

Many years ago, Quist worked on the infamous Manhattan Project, which was instrumental in the designing of the atomic bomb codenamed Fat Man, used to obliterate the seaside port of Nagasaki in World War II. This involvement has continued to weigh heavily on Quist's conscience ever since. Hearing the phrase "Say knife," he recognises a potential threat - one that is tied into a break in at a plutonium base. A group of young student activists has stolen several radioactive fuel rods, and are planning to construct their very own atomic device.

A vicar collapses during a sermon, and there are seemingly unrelated events, one involving John Ridge. The answers are out there, but are obscured by big business and profit margins.

A revolutionary new lipstick goes on sale, containing pheromones designed to act as an aphrodisiac in order to make the wearer more attractive and desirable to men. This prompts Quist and Bradley to begin an investigation into the effects that pheromones have on people, and how they can alter the illusion of free will.

A radical new procedure has been developed for treating violent criminals. The results are extremely positive, but Anne Tarrant is not convinced of its ethics.

Ridge continues his ecological crusade by warning against the dangerous side effects of the chemical insecticide known as D.D.T. upon the world's developing countries. He stages a publicity stunt by flying in an Indian family and setting them up in a tent in the middle of London's St. James Park. But the prank backfires when it is discovered that one of them is suffering from malaria.

Doomwatch is alerted to a laboratory where a new toxic gas is being developed for military use, available in a 'handy' aerosol can for easy application during conflict. But Quist and Anne's enquiry soon leads them to doubt that the scientists' safety measures concerning the storage of the gas may not be as secure as they think.

Quist is concerned by the fact that, approximately every one hundred years, certain extreme weather conditions arise which lead to an increase in the water level of the Thames - and just one inch higher would result in the whole of London flooding. Even more disturbing is the fact that this increase is imminent.

When John Ridge's father, Wilfred, becomes seriously ill, he decides to devote all his time to looking after him. Wilfred is then taken to hospital and put into the care of Doctor Cordell, but shortly afterwards he dies. Ridge is suspicious, and his investigations uncover a disturbing fact: Doctor Cordell is an advocate of euthanasia.

Dolphins have long been established as highly-intelligent creatures, and the United States Navy has now begun using them in their new program. They are training the dolphins to act as underwater saboteurs, able to attach magnetic explosive devices to the undersides of enemy ships. Quist investigates the matter, and discovers that these apparently docile creatures are capable of becoming deadly killers - something that he experiences firsthand.

Astrophysics lecturer Neil Tannahill receives an enigmatic note from Dr. Spencer Quist, former head of Doomwatch, and finds himself drawn into a sinister conspiracy involving Soviet nuclear waste secretly stored at a British nuclear facility.