In 2010 Los Angeles, 81-year-old Elise Dove has recently been diagnosed with Alzheimer's disease, a condition she personifies as a thief named Agnes. The diagnosis brings long-buried memories of her childhood friend Mariko Inoue to the surface, and Elise is determined to find Mariko before Agnes erases everything. Using the iPad her son Teddy gave her, Elise discovers a newspaper article about a Japanese American woman who returned to San Francisco from Tokyo after six decades. Without telling her adult children, Elise books a flight to San Francisco.
The narrative shifts to Davenport, Iowa, in 1943, when 13-year-old Elise comes home to find FBI agents arresting her father, Otto Sontag, a German-born chemist. Otto and his wife, Freda, have lived in the United States for nearly two decades but delayed applying for citizenship until after Hitler invaded France, making their petitions look suspicious. A collection of innocuous details forms the FBI's case against Otto as an "enemy alien" under Executive Order 9066, the wartime directive authorizing the detention of individuals deemed national security threats: his late father's World War I medals, a borrowed copy of
Mein Kampf, an offhand remark about bomb chemistry, and a comment about not wanting to fire on fellow Germans.
Otto is sent to an internment camp in North Dakota. With his accounts frozen, Freda struggles to support the family. Elise loses all her friends, and the family moves to a tiny cottage on the outskirts of town. When Otto's appeal is denied, he petitions to have his family join him at Crystal City, a family internment camp in south Texas, knowing this means they will all become voluntary detainees and that repatriation to Germany is a possibility.
At Crystal City, a fenced compound of tar-papered bungalows and watchtowers housing German, Japanese, and Italian families, Elise meets Mariko Inoue on the first day of school. Mariko is a Japanese American girl from Los Angeles who speaks unaccented English and wears an identical charm bracelet. Despite the expectation that the ethnic groups keep apart, the two become inseparable. Mariko shares the fantasy novel she is writing about a warrior princess named Calista, and the girls spend their afternoons working on the story and dreaming of a future together in New York.
Camp life settles into a rhythm, but tensions simmer. Two young Japanese Peruvian girls drown in the camp pool. Mariko's older brother, Tomeo, announces his intention to enlist in the 442nd Infantry Regiment, an all-Japanese American military unit, and is beaten by issei (first-generation Japanese) community leaders for his decision. Camp director O'Rourke intervenes and releases Tomeo from Crystal City. Mariko's father, Kenji, grows increasingly bitter, forbidding Mariko from seeing Elise and calling her "too American."
In December 1944, Elise learns her family is on a list for repatriation to Germany. Otto confesses he agreed to possible repatriation as a condition of the transfer to Crystal City, believing the war would end first. On the day of departure, Kenji prevents Mariko from saying good-bye, and Elise boards the bus without seeing her friend.
The family crosses the Atlantic on the
MS Gripsholm, a Swedish ocean liner that strikes abandoned mines entering Marseille's harbor. They travel by train into a devastated Germany. The family reaches Pforzheim, where Otto's mother lives, and Otto, Freda, and Elise are ordered to work at the family watch shop making fuses for German submarines. The uncles secretly teach them to produce defective ones as quiet resistance.
On February 23, 1945, Allied bombing destroys over 80 percent of Pforzheim, killing nearly 18,000 people. The family survives in a root cellar, but the house is half-destroyed. Elise's friend Brigitte is killed. Otto's uncles, their wives, and their niece Hilde die in the watch-shop cellar. Relocated to a small apartment in Stuttgart, Elise is attacked in an alley by two French soldiers during the occupation but saves herself by screaming in English that she is American. She tells no one.
American troops eventually arrive. A tattered letter from Mariko reaches Elise after months of transit, containing just six sentences. When Japan surrenders, Elise waits for more correspondence. Months later, a package arrives containing Mariko's unfinished notebook and a devastating final letter. Kenji has burned Mariko's American passport and arranged her marriage to Yasuo Hayashi. Mariko writes that she can never leave Japan and asks Elise to finish Calista's story.
At a café near the American base, Elise meets Private First Class Ralph Dove, a 23-year-old from Los Angeles, and over weeks of conversation tells him everything. Ralph proposes a marriage of convenience: He will bring Elise to California and grant a divorce whenever she wants. In Beverly Hills, Elise moves into the guesthouse at the Dove family estate. Ralph departs nine days later on a photography trip through Europe, leaving Elise at the estate with his older brother, Hugh, and his sister Irene's young children, Pamela and Teddy. Hugh, who has a congenital heart defect that kept him from military service, watches Elise with quiet curiosity.
Hugh deduces the marriage is not real, and Elise confesses everything. Rather than condemning her, Hugh hires a tutor so Elise can earn her diploma and offers steady kindness. When Ralph is killed trying to escape a Soviet prison in Poland, Hugh and Elise travel to Germany to collect the body. Their shared grief deepens into love. On the flight home, Hugh warns that his heart condition may prevent them from having children. Elise replies that she is not afraid.
They marry the following June. Unable to conceive, they raise Pamela and Teddy as their own after Irene's second marriage fails. Elise opens flower shops that employ young women aging out of foster care and discovers her gift: She is good at loving people. Hugh dies at 72.
In San Francisco, Elise arrives at the Ritz-Carlton and meets Rina Hammond, Mariko's daughter and the hotel's guest relations manager. Rina tells Elise that Mariko has stage four breast cancer and is receiving hospice care at home, then drives Elise to her house. There, Mariko lies in a hospital bed facing a window lined with hummingbird feeders. When Mariko awakens, she reveals a truth Elise never suspected: It was Mariko herself who sent Elise's letters back, consumed by jealousy that Elise still had her freedom. By the time Mariko tried to write years later, the Sontags had moved and the letter came back undeliverable. Elise forgives her immediately, telling Mariko they never stopped being friends.
When Mariko notices the notebook and asks how Calista escaped her tower, Elise tells her that Calista realized she had wings all along and flew out. Mariko asks where Calista went. Elise whispers that she went wherever she wanted, and Mariko's eyes close.
Mariko dies that night. In the morning, Agnes takes hold. Elise has forgotten Rina's name. Remembering only that she and Mariko once planned to go to New York, she tells a taxi driver to take her to the airport. She knows how to fly. All you need is a ticket and the sky. And wings.