Sam Kimura, a Japanese American veteran of World War II, learns that his sister Kei, whom he has not seen in nearly sixty years, has passed away. As Sam peruses items left by Kei for him, her memory transports him back to the Salinas, California. He recalls the turbulent events that led to his family’s evacuation from their farm to the wastelands of Wyoming in the Heart Mountain internment camp.

At Heart Mountain, the Kimuras, including their grandfather Ojii-san, suffer under the harsh conditions of camp. Sammy joins the Japanese American Citizens League (JACL) as a camp leader under the direction of its National Secretary, Mike Masaoka, and finds friendship and companionship with a volunteer quaker nurse, Hannah.  Sammy and Masaoka call for patriotism and rededication to America to demonstrate Japanese American loyalty. This rubs many in camp wrong, including Sam’s father, Tatsuo. Meanwhile, Kei, liberated from her daily farm chores and family obligations, finds her voice and a budding romance with Frankie, an agitator in the camp.

Meanwhile, Masaoka has organized the 442nd all-Japanese American regimental combat team and announced that he will be its first volunteer. He invites Sammy to join him, but Tatsuo rejects the idea when the government circulates a “Loyalty Questionnaire.” Sammy argues with his father, who has threatened to refuse to repledge his Allegiance.

Sammy tries to bring the camp together with a dance, but the night is hijacked by Frankie, who uses the occasion to stir opposition. Outside the dance, Sammy is beaten up as one of Masaoka’s perceived stooges. He seeks medical help from Hannah, and in a moment of rare privacy, the two share their feelings for one another. 

After answering “no” on the Loyalty Questionnaire, Tatsuo is arrested to be taken away to Tule Lake, a punishment camp for disloyals, while Sammy against the wishes of his older sister Kei, heads off to training camp to prepare to fight in the war.