Doctor Who: The Best of The Third Doctor Season 1 Episode 9 The Green Death, Episode 1

The Green Death is the ninth episode of season one of Doctor Who: The Best of The Third Doctor. In this episode, the Third Doctor and his companion Jo Grant arrive in the Welsh village of Llanfairfach, where toxins have been found in the local mine. The Doctor suspects that the mysterious Global Chemicals corporation, which has recently set up shop in the area, may be responsible.

As they investigate, the Doctor and Jo discover that the miners are suffering from a strange disease, which turns their skin green and causes them to behave erratically. Meanwhile, Global Chemicals' director, Stevens, is more interested in covering up the issue than finding a solution, and a group of environmental activists, led by the charismatic Professor Jones, is trying to expose the company's wrongdoing.

As the situation in Llanfairfach gets worse, the Doctor and Jo team up with Professor Jones and her team to uncover the truth behind the toxin, and find a cure for the diseased miners. Along the way, they encounter a strange computer known as BOSS, who seems to have a mind of its own and is controlled by Stevens.

The Green Death is a classic Doctor Who episode that explores themes of corporate greed, environmental activism, and the dangers of uncontrolled technology. It is also notable for introducing the character of Sergeant Benton, who becomes a recurring ally of the Third Doctor. With its mix of science fiction, action, and social commentary, The Green Death remains a fan favorite and is considered a highlight of the classic Doctor Who era.