Gratz structures the novel in alternating chapters, telling the stories of three child refugees from different countries, in different historical periods. This allows him to build rich characters his audience will identify with and care about, individuals with specific stories and from specific places and times, while making a larger point about the ongoing problem of children being forced to flee their home countries with their families. The structure of the novel makes clear that refugee crises are a continual problem in the world that must be reckoned with as an ongoing problem, not a one-time tragedy. His use of Cuba and Germany as countries that characters in one time period flee while those in another time seek as safe havens demonstrates the idea that no place is immune to the problems that lead to refugee crises and, by the same token, no place is permanently broken. Cuba was a safe place for the few passengers of the St. Louis who were allowed to land there, even though it is no longer safe by the time Isabel and her family flee. Even though Germany was unsafe for Josef and his family in the 1930s and ‘40s, by 2015, it is a safe place for Mahmoud and his family. 

Each of the storylines begins with an inciting incident that causes the family to leave home. Mahmoud’s family leaves Syria after a missile destroys their apartment building. Isabel’s family leaves Cuba after her father is the subject of police brutality and threatened with prison. Josef’s family is torn apart on Kristallnacht, when Nazi soldiers tear apart their home and Aaron is taken to a concentration camp. He is released after six months, with orders to leave the country. In every case, home has been a difficult place for some time before the families leave, showing the strong attachment people have to home, even when it becomes a dangerous place. By the time Mahmoud leaves Aleppo, the city has been under siege for so long that ten-year-old Waleed doesn’t remember a time before the war. Isabel’s story begins in 1994, five years after the Soviet Union withdraws monetary support from Cuba, causing the economy to collapse and hunger to become commonplace. Even before Kristallnacht, Aaron is forbidden to practice law, Josef is held up for ridicule by his teacher for being a Jew, and eventually neither he nor Ruthie is allowed to attend school at all. 

For all characters, the struggle to survive the danger of their journey as refugees drives the plot. Isabel expects her journey to be short and relatively simple, given that Castro is not opposing those leaving Cuba. However, the passage presents enormous physical dangers, from the tanker that nearly swamps the boat, to the storm that threatens to sink them, to the shark attack that kills Iván. Josef is initially relieved to be aboard the St. Louis, where refugees are allowed freedom and pleasures they have not had in years in Germany and the sailors treat them with respect. However, the ship becomes a trap when they are not allowed to leave in Havana, with his father’s increasing madness ending in his separation from the family and Otto Schiendick and the firemen tormenting the passengers. Mahmoud’s father believes they can get to Germany fairly easily, but instead they are attacked while still in Syria, repeatedly cheated in Turkey, and lose Hana when they nearly drown in the Mediterranean. 

Each story turns when a character takes action to save others. Isabel’s story pivots on Lito’s sacrifices of himself to draw the attention of the Coast Guard, allowing the rest of the family to arrive “dry foot” in Miami. After a lifetime of regret that he did not break the rules to help the passengers of the St. Louis, he gives his family a life in America. Mahmoud overcomes his fear of visibility and dares to defy the guards in Hungary, leading his family and the other refugees to freedom in Austria and beyond. While Josef himself does not survive the story, his sacrifice saves Ruthie’s life and makes possible the lives of her children and grandchildren and great-grandchildren. She is in Berlin to welcome Mahmoud because Josef saved her, and she pledges to help Mahmoud find Hana and bring her home, telling him he saved Hana as surely as Josef saved her.

Each plotline resolves as the characters make their way to a new home and begin to assimilate the new place into their sense of identity. Isabel declares as she first sets foot on shore in Miami that her brother is born an American and that she, while Cuban, will be American soon, too. Fitting the extended metaphor she uses of a song to describe her journey from Cuba, her story resolves at her audition for the school orchestra, an event she refers to as a “coda,” meaning the conclusion of a piece of music. As she plays the U.S. national anthem on her replacement trumpet, she infuses the song of her new country with the clave rhythm that is the heartbeat of Cuban music, showing how she is creating a hybrid identity as an immigrant. 

Mahmoud is surprised in Berlin to see that the people that have agreed to take his Muslim family in are Jewish, an indication of how different life will be in Germany than in the Middle East, where they would be enemies. Nevertheless, he immediately bonds with Ruthie, herself an example of a child refugee who has built a home and a life for herself. Ruthie’s home is in Germany, but a very different Germany from her childhood. She has ultimately returned to the country she was forced to flee and has reconciled the horrors of Nazi Germany with the country she and her family now welcome outsiders into. However, she has never forgotten what it is to be a refugee, as shown by her conversation with Mahmoud and her gift of a stuffed rabbit like her own Bitsy for Waleed. Likewise, Mahmoud and Isabel will never forget their experiences as refugees, and they will build identities that combine what they know of their countries of birth and what they learn in their new homes.