On an extended visit to her cousins in London, Lizzie's passion for plants and trees is fuelled by visits to the newly opened Kew Gardens. Like her elder cousin, who wants to defy her middle-class upbringing and become a nurse, Lizzie has ambition and the will to go against the conventions of her Victorian peers. She wants to be a gardener, and the first step towards her dream is to plant a walnut in the garden of 6 Chelsea Walk.