Del Boy purchases a pile of bricks and discovers several boxes of lead underneath.
Rodney finds some old paperwork with the lead and discovers that it is intended for a do it yourself nuclear fallout shelter.
The rest of the episode is set in the shelter, where the conversation turns to war and the potential aftermath of the impending conflict.
The episode ends with Del dreaming aloud of what could become of the world in the event of nuclear fallout, while the camera zooms out to reveal the location of the Trotters' fallout shelter; on the roof of their tower block, Nelson Mandela House.
[1] Ronnie Hazlehurst: Original Theme Tune Note: In the original series 1 broadcasts of Only Fools and Horses, the theme tune was very different to the version adopted from series 2, which became the standard version known today.