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.

Ridge and Hardcastle are sent on what seems a simple enough assignment, but stumble onto a major government cover up in an abandoned English manor.

After a long-haul flight Dr Quist's reputation is put seriously in doubt when he arrives drunk to a meeting with the Prime Minister. Is it a simple case of jet-lag, or sabotage?

The Doomwatch team investigate the mysterious outbreak of a deadly subtropical disease which somehow has cropped up on an isolated island off the coast of the UK.

A young boy dies while attempting to retrieve a ball from a high roof, but the cause of his death is not from falling. Doomwatch investigate.

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?

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.