Her Fearful Symmetry

The novel's title is inspired by "The Tyger",[4] a poem by the English poet William Blake, which begins "Tyger! Tyger! burning bright / In the forests of the night, / What immortal hand or eye / Could frame thy fearful symmetry?".

Considering the setting of the novel, some critics have also pointed out a potential verbal pun in the novel's title, since in received pronunciation "symmetry" and "cemetery" are almost homophonous.[5] There is also a physical symmetry in two of the main characters – identical twins with mirrored internal organs.

Elspeth dies of leukemia. Her apartment, located beside Highgate cemetery in London, is left for the daughters of Edwina, her estranged twin sister. Elspeth's nieces, identical twins Julia and Valentina, have always done everything together, with Julia being the more dominant twin. Valentina has asthma and has a heart valve that hasn't been properly formed, making her slightly ill. They move to London and take up residence in the flat. Robert, Elspeth's former lover, lives in the apartment below them. Robert works as a tour guide in the cemetery as a way of learning more for his thesis on the cemetery. Valentina begins falling in love with Robert and he reciprocates, mainly due to her resemblance to Elspeth.

Martin, a man whose wife, Marijke, has left him because of his obsessive compulsive disorder, lives in the apartment above. Julia befriends Martin and gives him Anafranil (a pill for OCD), pretending that it is a vitamin. Martin is aware that she is giving him the medication, but feigns ignorance.

Unknown to anybody for the first year, Elspeth is trapped in her apartment as a ghost, invisible and mute. However, Valentina discovers her awareness of Elspeth's moods. One day, she sees Elspeth in the apartment. The twins find a stray kitten near the cemetery. After several failed attempts, they lure it into their apartment and begin taking care of it. One day, while playing with the twins, the kitten abruptly drops dead. The twin figure out that the kitten's soul has been caught on Elspeth's hand. Elspeth puts the kitten's soul back into its body and bring it back to life.

A recurring theme throughout the story is Valentina's discontent with being one half of a whole (her twinship with Julia). She is the weaker twin both physically and emotionally. Julia calls her "Mouse" because of her fearful attitude toward everything. As the story progresses, Valentina becomes stronger emotionally and decides she must break away from Julia to be able to live her life.

Valentina plans to fake her death. She asks Elspeth to temporarily take out her soul, and instructs Robert to preserve her body. Horrified, Robert refuses to participate. He decides to read the diaries and letters that Elspeth left him when she died. He finds out that there was no rift between Edwina and Elspeth, but rather a secret they shared that made it impossible for them to be together again: for decades, the two woman have been assuming each other's identity. The recently deceased "Elspeth" (actually Edwina) is the mother of Julia and Valentina. Decades ago, Elspeth was engaged to Jack, an American working in London. Insecure about his love, she pretended to be Edwina and made advances toward Jack to test him. Jack knew that she was not Edwina, but played along. On April Fool's Day, Jack and (the real) Edwina got drunk at a party and they had sex, which he was too drunk to remember. Elspeth marries Jack, but it was Edwina who moved to America with him, and gave birth to Julia and Valentina. When the girls were four months old, Edwina brought them to London, and they switched places so that Elspeth could be together with Jack. Edwina had been living away from her children until her death.

Later, Valentina, Robert and Elspeth proceed with the plan. "Elspeth" removes and holds Valentina's soul. Robert then makes it look like an asthma attack killed Valentina. Julia discovers the body and is devastated. A funeral is held with Valentina's coffin being interred in the family mausoleum in Highgate Cemetery. Later that day, Robert retrieves the body and takes it to the flat. When the body wakes up, Robert discovers that the soul inside Valentina is "Elspeth." She tells Robert that Valentina's soul had dispersed, and she decided to take over the body.

Valentina becomes a ghost trapped inside the apartment. Julia continues living there, hoping to one day see her as Valentina had seen Elspeth. Eventually, they are able to communicate, and Valentina learns how to leave the apartment. While Julia is sad for her sister's fate, Valentina is free and happy.

Martin moves out of his apartment and his son Theo lives there. Soon after, Julia and Theo begin dating.

One day, after a run in with Julia who is suspicious but uncertain, "Elspeth" (in Valentina's body) informs Robert that they need to leave England. She proposes moving to Sussex, where she always wanted to live. Robert realizes that "Elspeth" is manipulative and always gets her way and that brings harsh feelings among the family. They move to Sussex, where the relationship between Robert and "Elspeth" deteriorates with Robert ignoring her most of the time. She delivers a baby boy and one day, shortly after the child is born, "Elspeth" returns to their little cottage after a walk and discovers that Robert's thesis has been completed and is lying on the table. Robert is gone, never to return.

AudioFile magazine called Niffenegger "a master storyteller" and praised her "skill in bringing plausibility to the unthinkable" as well as audiobook performer Bianca Amato's narration.[6]

• Interview with the author about the book
• Book review in the Guardian
• Book review in the New York Times