The novel is a fictionalized account of the life of Lili Elbe , one of the first transgender women to undergo sex reassignment surgery. The author has stated that the novel does not try to tell a true story. Ebershoff not only imagined most of what he wrote about Elbe's inner life, but also fabricated all of the other characters in the book, most important among them Wegener's blue-blooded American-born wife, Gerda Wegener.
The story takes place in Copenhagen, Denmark. Lili Elbe then presenting as male and using her birth name is happily married to her wife, Gerda Wegener. Lili was raised with her best friend Hans. Gerda was raised in California with her twin brother Carlisle.
During their separation, Gerda marries another man and has a child, with the child unfortunately dying at birth and her husband dying of tuberculosis.
Gerda moves back to Denmark and marries Lili. The couple become painters; Lili specializes in painting landscapes and Gerda specializes in painting portraits. One day, Gerda's friend Anna Fonsmark cancels her scheduled painting session with Gerda.
Gerda, needing to have the painting finished as soon as possible, requests Lili to model in Anna's place. The session is interrupted when Anna suddenly enters their home, and Anna is the first to give Lili her new name. Some time later, Lili and Gerda are invited to the annual Artists' Ball, and Gerda convinces Lili to wear a dress again. During the ball, Lili meets a man named Henrik Sandahl, and the two start a short-lived relationship, which Gerda discourages, fearing that if Lili does not tell Henrik of her marriage and her assigned birth gender , she would be hurting him by deceiving him.
