In 1940 England, feminist poet Vita Sackville-West gets a phone call from Violet Keppel Trefusis which triggers a flashback to 1917 where Violet first came for a visit at Vita's country house.
Vita and Violet's romance grows which leads to Vita dressing up as a man (an injured soldier on leave from the front) and meeting at hotels and boarding houses in London to continue their romantic tryst.
With the end of World War I in 1918, Vita returns to her family home to her husband and sons. However, she continues to write and correspond with Violet, who is still being courted by Trefusis who is clearly devastated by his inability to win her over with gushing adoration and endless indulgences.
In 1921, Violet is unhappy with her celibate marital life. Vita manages to get in touch with her to persuade her to leave her husband and run away with her, first to Paris and then to Greece where they can live out a life together.