All initially goes well. They have four beautiful, gifted, gentle children. Then Harriet becomes pregnant again and the child in her womb is clearly different. He mercilessly terrorizes Harriet from within. Harriet is relieved to finally give birth to this new child, Ben, but Ben's raucous prenatal treatment is nothing compared to what comes next.
David and Harriet's fifth child is different and they clearly have no idea how to handle him. He is a monstrous baby who is never sated when fed and seems immune to the calming benefits of affection. What are they to do? Ben grows and grows into a troll-like child and he possesses a physical strength that is juxtapositioned against a demeanor that appears impervious to human tenderness or empathy.
Professionals are called in but none of them seem able to comprehend Harriet and David's horror. They seem to either want to mindlessly exterminate Ben or vilify Harriet and David for not accommodating this fifth child with love even though he doesn't conform to their first four children's characteristics.
This is a horrifying story and incredibly haunting. Lessing is accomplishing a couple of key points with this book. First, she is trying to illustrate the all-encompassing world of having a special-needs child. The arrival of Ben initially consumes Harriet but soon infiltrates each member of the family. Could the family's eventual unravelling have been avoided?
Secondly, the placement of Ben's birth and upbringing makes him a metaphor for Britain in the 1980's. The staid world of Harriet and David, rooted in England's hierarchical traditions can not make sense of the nihilistic violence seen in those elements of post-war Britain that manifested itself in the Punk movement or the methodical, systematic plague of football hooliganism.