The story starts in 1815 in Brussels. It was before the final collapse of the Napoleon ruling - before the Battle of Waterloo. One evening, Sophia Trenchard has her last meeting with Bellasis at the costly ball. General Wellington visited the celebration and stood there even receiving an invitation to the battlefield. He did that trying not to spread the panic among the people.
The largest part of the story takes place in 1840s, and Sophia is long dead. She died 25 years ago during a childbirth. Her parents mourn her for years. They have another child, who lives in an unhappy marriage without children. His name is Oliver and he wants to be loved by his as his sister was. But James cannot accept Oliver, who is famous as a drunk.
He is nothing like his father. James is a very successful man and very kind man. Once he was a supplier to the military. With the years passing, he became a successful builder. Anne helped him as good wife could.
In Belgravia Julian Fellowes tells us an intricate and beautiful story about the life of the son, who killed his mother at the moment of the birth. This death will start the series of changes, which will affect not the Oliver's life only. The influence of this long past event will be felt even the very powerful people of 19th century London.