In autumn of 1941, Rilla announces her engagement to Alex and asks Allina to witness a civil ceremony that Saturday. Alex’s visible discomfort when Karl’s name comes up signals to Allina that he is part of Karl’s network. The signal she has been waiting for arrives moments later: a telephone call from Prague reporting that Karl’s aunt is gravely ill and Allina must travel to Basel at once. She is told to depart within a day.

Alex offers to drive Allina and Katrine to Karlsruhe that evening. Allina spends the afternoon in anxious preparation, makes a last visit to the sunflower garden, then returns to Hochland Home, where the children give her a surprise farewell party with hand-painted pictures. She gives Rilla her wedding veil and gloves as a parting gift.

During the four-hour drive, Allina falls asleep; when she wakes she questions Alex. He confirms he knows only his own part in the plan and that Karl had him delay his leave specifically to escort her. He reassures Allina that Rilla is stronger than she appears and will not hold the years of secrets against her. At Karlsruhe station, a last-minute track change throws the departure into confusion. With minutes to spare, Alex fulfills Karl’s final instruction—a kiss on Allina’s forehead on Karl’s behalf and one on Katrine’s cheek from her father—before calling after them to have faith as the train departs.

Allina and Katrine arrive after midnight at the Binningen home of Karl’s aunt, Adele von Strassberg. Adele is a tiny, sharp-featured woman with surprising physical strength. The household quickly settles into something resembling a family routine.

Adele takes Allina to her parlor, a cluttered room overflowing with valuable antiques. Allina correctly deduces that Adele sells pieces from the collection to fund the transport of Jewish children out of Germany, and that the room’s disorder reinforces her cover as a harmless eccentric. Adele explains that resolution to Karl’s plan is expected within a fortnight, and that Allina’s apparent return to Germany must be staged while she and Katrine remain hidden. Two young girls from a recent transport of 46 children are still in the house. Adele opens a concealed door behind a grandfather clock, revealing stairs to a cellar shelter.

In the cellar, Allina meets Klára, aged nine or ten, and her younger sister Sofie, who has been entirely unresponsive since arriving. Allina spends the following days reading to the girls and helping Adele with household tasks. Klára eventually reveals that she and Sofie are Polish orphans smuggled out of Theresienstadt hidden inside a coffin; Sofie became convinced they were dead during the ordeal. When a childless farming couple, the Bryners, arrive to take the girls as foster children, Sofie produces a faint smile for the first time.

Adele instructs Allina to make conspicuous public appearances nearby, outfitting her in a memorable, wide-brimmed plumed hat designed to ensure she is noticed and remembered. On their return, a courier has delivered a note from Karl bearing the number 48 and an intimate farewell. Adele interprets the number as a directive to stage Allina’s fake departure within 48 hours; Allina understands the personal sign-off as a departure from their agreed protocol and a final goodbye. Adele arranges for her cook Lisel and Lisel’s young sister Franka to serve as decoys—dressed in Allina’s clothes and wearing the hat—while Allina and Katrine go into hiding in the cellar.

At Theresienstadt, Karl and his colleague Markus stand in the camp courtyard awaiting execution by a firing squad composed of their own soldiers. Commander Jockel reads the formal charges of treason for plotting to kill Hitler. When asked for last words, Karl spits near Jockel’s boots and declares he will see him “in hell.” Jockel strikes him across the face. One of Karl’s long-serving soldiers, Müller, steps forward in tears to place a blindfold over Karl’s head. He briefly grips Karl’s shoulder before returning to the squad. A falcon circles overhead, and for a moment every man in the courtyard pauses before Jockel gives the order to fire.

As Karl lies dying, his consciousness separates from his body. He perceives Allina and Katrine together in a warmly lit room, safe and unharmed. Then his deceased parents appear, looking younger and more vivid than in any memory he holds, and beckon him forward. Karl’s soul releases and moves into the light.

Allina and Katrine spend five days confined to the cellar. Katrine’s initial restlessness gives way to growing withdrawal and silence. Allina establishes a daily routine to keep them both anchored, and each time Adele receives a visitor, the parlor radio is switched on as a warning. Allina keeps Katrine quiet with a game Lisel devised called Mouse in the House.

On the sixth morning, a police officer named Kupper arrives asking for Allina. Adele insists her niece returned to Germany nearly a week ago, but Kupper reports Allina is missing from both Hochland Home and Starnberg. He then reveals that Karl is dead, executed by firing squad. The fact that Adele received no advance warning tells her the resistance communication chain has broken and they have lost critical time. She cuts Allina’s hair, tells her she must leave for the US without delay, and asks Elias, her driver, to prepare the car. After a tearful farewell with Lisel, Allina and Katrine depart.

In 2006, Allina tells Katrine the details of their escape: Elias drove without rest through Switzerland, south toward Bern, then across France, into Spain, and finally to Portugal, where they waited in Lisbon for six weeks before securing passage. At each stop, Adele’s network supplied fresh papers, vehicles, and food. Allina then reveals that the final set of papers Karl had prepared were in the name Allina Strauss—her former identity, restored to her as a parting gift.

Katrine asks why she was not raised in the Jewish faith. Allina explains that she was deeply angry at God for permitting such cruelty, and that a brief attempt at Shabbat services after Katrine left for college brought back too much grief to sustain. Katrine offers to attend services with her, and Allina agrees.

In 2010, Katrine visits her mother’s grave at a cemetery in Englewood, New Jersey. Allina died on October 7, 2009, aged 89, and is buried as Allina Strauss. Katrine reflects on the years following their long day of shared truth in 2006: They cooked and danced together, Allina taught Katrine German so she could read Karl’s wartime letters, and together attended Shabbat services, where Allina eventually found friendship and peace. Katrine places sunflowers at the grave, intending to keep telling her own daughters the full family story—the rescues, the losses, the sacrifices—because, as her mother showed her, truth is the only remedy for the damage that secrets cause.