Peter is a twelve-year-old boy living in Riswyk, Norway, who becomes the president of the newly formed Defense Club. He leads his peers in a dangerous operation to transport gold past occupied forces on sleds. Eager for adventure, he initially romanticizes the idea of outsmarting soldiers but quickly learns that real bravery involves acting responsibly despite genuine fear.

Victor is Peter and Lovisa's adventurous uncle. As a professional fisherman who commands a fleet of vessels, he is patriotic and clever. He devises the plan to use the local children to transport Norway's gold bullion to his camouflaged ship, the Cleng Peerson.

The Commandant is a terrifying, aggressive German officer who views the local Norwegians with utter contempt. Unpredictable and prone to violent outbursts, his presence poses a constant, looming threat to the children's secret operation as he attempts to force them back into school and investigates suspicious activities.

Lovisa is Peter's ten-year-old sister who actively participates in the dangerous scheme to move gold out of Norway. She displays fortitude and dry humor in the face of the occupation, remaining stoic even when confronted directly by terrifying soldiers. She maintains a calm exterior that belies her young age.

Lars is a banker and the father of Peter and Lovisa. Initially terrified at the prospect of his children facing danger, he accepts their necessary role in the resistance. He teaches Peter how to move through the woods discreetly at night and eventually joins the Norwegian army to fight the invading forces.

Mrs. Lundstrom is the caring mother of Peter and Lovisa. She actively participates in the resistance efforts, helping transport gold on a bobsled to avert suspicion. She devises a clever plan to create a fictional epidemic, keeping the children out of school so they can continue their work.

Helga is a bold and daring girl who acts as one of the four team leaders in the Defense Club. She possesses a natural fearlessness and takes the initiative to lead the other children past armed sentries, reasoning that her gender and age make her appear less suspicious to the guards.

Michael is Peter's good friend and a dependable member of the local community. He is appointed as one of the four team leaders of the Defense Club, responsible for guiding a group of children as they transport heavy gold bricks past the military encampment.

Per Garson is the elderly servant of the Lundstrom family. Despite his age, he is a skilled skier and a wise figure who physically loads the heavy gold bricks onto the children's sleds. He offers them cautious advice about the realities of their undertaking and predicts the weather based on his joints.

Jan Lasek is a young Polish student who was imprisoned by the secret police and forced to work as a reluctant translator. Trapped in an enemy uniform, he despises the occupying forces who destroyed his home city of Cracow and desperately wishes to escape to America.

Rolls is Uncle Victor's loyal first mate on the Cleng Peerson. A steadfast and dependable sailor, he assists Victor in organizing the maritime logistics of the smuggling operation and directly handles the heavy gold deliveries at night.

Herr Holm is a local farmer and a dedicated adult member of the Norwegian resistance. His farm serves as a crucial safe haven and resting point for the children on their return journeys from the Snake fiord. He actively monitors the surrounding area for spies.

Dr. Aker is the town doctor of Riswyk. Using his medical authority to support the resistance, he implements Mrs. Lundstrom's idea to fabricate a contagious measles epidemic, applying red disinfectant to the children's faces to keep the schools closed.

The German Captain is an officer stationed in Riswyk during the early days of the occupation. Unlike the ruthless Commandant who replaces him later, he is polite and nostalgic. He kindly moves his troops so the local children can enjoy their sledding undisturbed.

Mr. Anders is the local schoolmaster in Riswyk. He quietly leaves the town shortly before the full occupation takes hold to join the Norwegian Army and fight the invading forces in the south of the country.