The book is set in Norway in 1940, and starts out with four Norwegian children, Peter, Michael, Helga, and Lovisa playing on their sleds after school. Later, when the children are in bed, Peter wakes up to hear several men talking downstairs and goes down to eavesdrop. The men; Including Peter's uncle and father, need to smuggle gold past the Nazis, who have not yet invaded Norway. Peter's uncle, Uncle Victor, sees Peter and tells the other men that the solution to their problem lies with the children.

The next day, the townspeople build bomb shelters, and the day after that, the Nazis invade Norway. Uncle Victor tells Peter, Michael, Helga, and Lovisa about the men's plan.[7] The plan is that all the children above ten years of age in their school will carry the gold past German sentries on their sleds and leave it by Uncle Victor's ship, which would then take it, for safekeeping, to America.[8][9]

This plan works for two weeks until the Nazi commander in their town wants to re-open the school, which would prevent the children from sledding. The town's doctor creates a false epidemic that affects only the smaller children and paints them from head to toe with red dots. Then he tells the German commander that it is impossible to start school with this epidemic going around. He also says that he encourages the healthy children to stay outside. So, the school stays closed, and the children keep sledding.

The children are later in the story discovered by a Nazi, whom Uncle Victor and Rolls, his sailing mate, take captive. Their prisoner denies that he is a Nazi, although he is in a Nazi uniform. He tells them that his name is Jan Lasek, and that he is a young Pole who was captured by the Nazis when they invaded Poland, and forced to serve in the German army. He then asks Uncle Victor to take him to the United States because he says he has relatives there. Uncle Victor agrees, under the condition that Jan be kept prisoner until the ship departs, in case this is a Nazi trick.

At the very end of the story, all the gold is safely away on the ship going to America. Peter and Jan Lasek, the young Pole, also embark.