First performed in 1978, Plenty is about British post-war disillusion. Susan Traherne, a former secret agent, is a woman conflicted by the contrast between her past, exciting triumphs - she had worked behind enemy lines as a Special Operations Executive courier in Nazi - occupied France during World War II - and the mundane nature of her present life, as the increasingly depressed wife of a diplomat whose career she has destroyed. Viewing society as morally bankrupt, Susan has become self-absorbed, bored, and destructive - the slow deterioration in her mental health mirrors the crises in the ruling class of post-war Britain.

Susan Traherne's story is told in a non-linear chronology, alternating between her wartime and post-wartime lives, illustrating how youthful dreams rarely are realized and how a person's personal life can affect the outside world.