Gretel has lived in London for decades, never speaking of her childhood in Nazi Germany as the daughter of a concentration camp commandant.

Seeking security, Gretel’s mother courts Rémy Toussaint, a wealthy man and former resistance member in the hope that their eventual marriage will guarantee their future.

However, Gretel becomes infatuated with Emil, an assistant in his father’s haberdashery shop, whose older brother was a resistance fighter executed by the Germans.

Gretel moves to Australia, befriending Cait Softly, a lesbian Irishwoman who was physically abused by her father for falling pregnant; the beatings then resulted in her suffering a miscarriage.

At the pub where Kate works, Gretel spots Lieutenant Kurt Kotler, a former German soldier who served under her father.

They discuss her anger and his support for the Nazi regime, with Kurt pointing out that Gretel is angry with him as a means of escaping from her own guilt.

In the hospital, Edgar informs her about David’s past; how he was born in Prague and escaped with his grandparents after the occupation, and that parents and sister were delayed and disappeared, ultimately being murdered in Treblinka extermination camp.

Gretel expresses regret that she never told him why it was so important to her that they move into Winterville Court, a block of flats in Mayfair, after he received an inheritance early in their marriage.

This behavior proves to be too much for Gretel, who eventually calls the police on Alex in an attempt to safeguard his wife and son, but nothing comes of their investigation.

This leads Gretel to take drastic action; by inviting Alex into her flat, slitting his throat, and handing herself over to the police following Caden's wedding.

[3][4] Booklist's Margaret Quamme praised Boyne's engagement with the novel's main themes of guilt and complicity with violence but criticized the plot for containing too many coincidences and chance encounters.

"[8] The New Statesman's Ann Manov was even more blunt, describing the novel as "childish drivel" and as having "utterly fail[ed] in its stated purpose" of furthering genocide education.

"[9] Publishers Weekly wrote that the novel served as an acceptable sequel to The Boy in the Striped Pajamas but that it wasn't capable of fully standing on its own.