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?

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