"The House of Riverton: A Novel" tells the story of Grace Bradley, a 98-year-old woman who was formerly a housemaid at Riverton Manner in the 1920s. Grace is visited by a young director who is making a film about the suicide of a famous poet, Robbie Hunter, that occurred at the manner. The novel details Grace's experiences in the 1920s living with the children at Riverton, Hannah and Emmeline, and Robbie Hunter, as well as her place in his death.
The main conflict of the novel revolves around sisters Hannah and Emmeline both falling for the poet and WWI-veteran Robbie Hunter. Hannah is unhappily married to another man in London, but she begins an affair with Robbie after he shows her the life she always wanted to have. Robbie and Hannah essentially use Emmeline as a way to see one another, as Robbie frequently calls on Emmeline but actually is slipping secret notes to Hannah with information for their secret rendezvous. They eventually make a plan to run away and start a new life together by Hannah faking her own death.
During a party at the manner, Grace, the housemaid, finds Hannah's suicide note in her room and runs to Emmeline so they can stop her. However, upon arrival, Hannah tells Emmeline that she and Robbie are going to run away together. Jealous, Emmeline takes out a gun and threatens to shoot herself. During this time, fireworks are going off, triggering shell shock in Robbie and causing him to try to make Hannah shoot Emmeline. Ultimately, Hannah must wrestle the gun away and shoot Robbie to save her sister; Emmeline plays it off as a suicide to the public and the police. In the present day, Grace, after finally revealing her long-kept secrets, is able to die peacefully.