It's 1945, and the world is in the grip of war. Hideki lives with his family on the island of Okinawa, near Japan. When World War II crashes onto his shores, Hideki is yanked out of school and drafted into the Blood and Iron Student Corps to fight for the Japanese army. He is handed a grenade and a set of instructions: Don't come back until you've killed an American solider. Ray, a young American Marine, has just landed on Okinawa with his squad....

Although separated by continents and decades, Josef, a Jewish boy living in 1930s Nazi Germany; Isabel, a Cuban girl trying to escape the riots and unrest plaguing her country in 1994; and Mahmoud, a Syrian boy in 2015 whose homeland is torn apart by violence and destruction, embark on harrowing journeys in search of refuge, discovering shocking connections that tie their stories together.