Set in Seattle, Washington, during World War II, the novel follows eleven-year-old Hobie Hanson as he navigates sacrifice, loyalty, and what it means to be brave while his father flies bombing missions over Europe.
On January 1, 1944, Hobie chases his best friend Scooter Adair's car on his bicycle, trying to say good-bye as Scooter's family moves to Portland. Hobie's German shepherd, Duke, runs alongside him. At home, a neighbor remarks that the Army could use a dog like Duke. Hobie's mother reassures him there are many ways to help, but Hobie privately compares himself to his father, Second Lieutenant Palmer Hanson, who left the family fishing boat, the
Lily Bess, to fly B-24 bombers in Europe.
At school, a new boy named Max Klein sits at Scooter's old desk. A bully named Mitch Mitchell mocks Max's German-sounding last name with a Nazi salute. Catherine Small, a confident classmate, invites Hobie to join her and Max for wall ball, but Hobie makes an excuse. That afternoon, Mitch steals Hobie's bike and kicks him, and Duke lunges to protect Hobie. A man named Mr. Rasmussen, the Assistant Regional Director for Dogs for Defense, a program that recruits civilian pets for military service, witnesses the scene and praises Duke's training. He gives Hobie his card, suggesting Duke could ship out that weekend.
Days later, a letter from Dad reveals his required missions have been increased, meaning he will be gone even longer. That night, Hobie studies a photograph of his father, Uncle Tryg, and the late Grandfather Hanson, remembering the family saying that courage does not always roar. The next morning, he tells his mother and seven-year-old sister, June, that he has decided to donate Duke. June bursts into tears. On Saturday, Hobie fills out the Dogs for Defense form, learning that most dogs remain in the United States as guard dogs but that the Army decides placement. He writes that Duke must be returned after the war. He loads Duke into Mr. Rasmussen's car and watches it drive away.
At school, Max quietly affirms that Hobie did the right thing. Catherine recruits both boys for her wall-ball team, and they beat Mitch's team. Hobie feels a flicker of hope that the war will end and both Dad and Duke will come home.
In February, a letter from Duke's handler, Private First Class Marvin Corff, reveals that Duke has been assigned not to guard duty but to the 3rd War Dog Platoon of the Marines at Camp Lejeune, where he is training with explosives. Upset, Hobie writes back claiming his sister is devastated and asking Corff to send Duke home. Corff gently declines, explaining that he and Duke are now a team. Hobie's first scheme fails. In April, after helping a girl train her disobedient dog, Hobie recalls that Duke's only unbreakable habit is chasing squirrels and writes Corff a second letter warning about the problem. Corff replies that Duke is the most disciplined dog in the unit and that they have orders to ship to California. The second scheme fails too.
Meanwhile, Hobie's friendship with Max deepens. They trade comic books, and when Mitch breaks the wing off Hobie's B-24 spotter model, Max's grandfather, Opa Klein, a skilled woodworker, repairs it. A letter from Dad expresses deep pride in Hobie for donating Duke. Hobie hides it, guilt-stricken because Dad would not be proud if he knew about the scheming letters.
At the class Memorial Day program, Max shares a coconut-shell belt buckle from his cousin, a radio operator on the Navy ship USS
Enterprise who saved two men after the attack on Pearl Harbor, challenging Mitch's earlier attempts to brand Max as disloyal. At lunch, Mitch points out that California means Duke is headed for the Pacific war zone. Hobie realizes with horror that Duke is going to war.
Over the summer, Hobie plays baseball with classmates including Marty, Preston, Catherine, and Max, who makes a spectacular catch that silences Mitch. One day, Hobie finds Max in an abandoned shed freeing a stray mutt from tin cans tied to her tail. Max names the dog Pepper and grows deeply attached.
On July 20, a Western Union telegram announces that Dad is a prisoner of war. Hobie, furious and grief-stricken, calls Mr. Rasmussen to enlist Pepper in Dogs for Defense, reasoning that a replacement dog will prompt the Marines to send Duke home. Before he can tell Max, Max arrives with joyful news: His mother has agreed to let him keep Pepper. When Max learns what Hobie has done, he accuses Hobie of never being a real friend, only using him for Pepper, and of never standing up for him against Mitch. Hobie recognizes the truth. He has been a "halfway friend." He cancels the arrangement and instead writes a genuine letter to Corff, sharing Duke's warning signal: When Duke's ears perk up, trouble is near.
A postcard from Dad at Stalag Luft 1, a prisoner-of-war camp in Barth, Germany, confirms he is uninjured. In late August, a letter from a nurse at the naval hospital in Pearl Harbor reveals that Corff has been wounded. During the battle on Guam, Duke's ears perked up to warn of an ambush, and Duke took the bullets meant for Marv, saving his life and the lives of the patrol. Both are recovering. Shaken, Hobie confides everything to Uncle Tryg while they work on the
Lily Bess. Uncle Tryg shares how he lost the use of his arm through a youthful mistake on the boat and tells Hobie that each man must learn his own lesson. Hobie reflects that bravery takes different forms: Grandfather Hanson's bold, roaring kind; Dad's willingness to sacrifice; and Hobie's own quieter, steadier courage.
The friendship with Max begins to mend when Hobie helps Max deliver newspapers, and Max hands him a piece of gum as a peace offering. In October, the school learns that Mrs. Thornton, Hobie's former fifth-grade teacher, has lost her husband in combat in Italy. In the cloakroom, Mitch attacks Max, calling him a "dirty Kraut." Max stands his ground calmly. Hobie steps to Max's side, and classmates Marty, Preston, Catherine, and Dorine Bunch all join them. Mitch drops his fists and walks away. Hobie has finally stood up for his friend.
On December 18, Corff arrives to return Duke. Duke is thinner and more muscular and stays close to Marv rather than running to Hobie. Marv confirms that Hobie's letter about Duke's warning signal saved the entire patrol. Hobie confesses his shame over the earlier scheming letters, and Marv assures him that wanting Duke back only proved Hobie loved the dog. When Marv prepares to leave, Duke follows him to the car and jumps in. Hobie freezes, terrified Duke will choose Marv. After a farewell lick, Duke hops out, runs to Hobie, and nudges a dirty tennis ball into his hand. Hobie throws it as far as he can, and Duke snatches it before it hits the ground.
On May 8, 1945, V-E Day (Victory in Europe Day), a telegram brings joyous news: Stalag Luft 1 was liberated, and Dad is free. On June 30, as the family prepares for Dad's homecoming party, Hobie runs errands with Duke trotting beside him. He challenges Duke to a race home, confident that this time he just might win.