Audrey Hepburn, known for her roles in the classic Hollywood films “Breakfast at Tiffany’s” and “Roman Holiday,” also played a more dangerous role when she was a teenager: a resistance spy against the Nazis.

The icon, who died in 1993, kept most of her life quiet despite the fame. Throughout the years, she hinted about her involvement with the Dutch resistance during World War II.

In a new book, “Dutch Girl: Audrey Hepburn and World War II” author Robert Matzen sheds light onto the little-known areas of her life during that period.

“For all that she would become—Academy Award-winning actress, Givenchy fashion plate, and international jet setter so at home on the Riviera or in Rome or Paris—the war years remained all too close,” Matzen wrote, according to the New York Post.

Hollywood legend Audrey Hepburn was a WWII resistance spy https://t.co/2hMlBoIWKK pic.twitter.com/mNIBMclSIv — New York Post (@nypost) April 10, 2019

Her work as a spy during the Dutch resistance against Nazis may come as a surprise since her parents were Nazi sympathizers.

Despite being born into an upper-class family in 1929, Hepburn grew up rather poor. Even with her mother’s status as Dutch noblewoman, Hepburn said, “My mother didn’t have a dime.”

On top of that, her parents divorced when she was 10, which was hard on her.

“It tortures a child beyond measure. They don’t know what the problem was. Children need two parents for their [emotional] equilibrium in life,” she said, according to the New York Post.

That was the same year World War II broke out.

Thank you @people magazine for this beautiful article about #AudreyHepburn’s chilhood past & her survival from Nazis during WWII. pic.twitter.com/FjVFyOYaYL — S➰G (@InTheGoodOl) April 8, 2019

When German troops invaded the Netherlands in 1940, Hepburn recalled, “The first few months we didn’t know quite what had happened … I just went to school.”

Despite the town being overrun with German signs and swastikas, the only thing that Hepburn noticed were the contents of lessons, according to the New York Post.

“In the schools, the children learned their lessons in arithmetic with problems like this: ‘If 1,000 English bombers attack Berlin and 900 are shot down, how many will return to England?'” Hepburn recalled.

During that time, dance became Hepburn’s escape.

“Guards were posted outside to let us know when the Germans approached. The best audiences I ever had made not a single sound at the end.” More on her Resistance work in @robertmatzen‘s Dutch Girl: Audrey Hepburn in WWII, out this month. #TCMParty pic.twitter.com/PyF3JkPCce — Sister Celluloid (@sistercelluloid) April 2, 2019

The turning point came in 1942 with the death of her uncle, Otto van Limburg Stirum, according to the New York Post. Hepburn’s uncle was captured, forced to dig his own grave, tied to a stake, and then executed.

His death caused Hepburn’s mother to turn against the Nazis and change her allegiance to the resistance.

Dancing was one of the ways Hepburn helped when she joined Dr. Hendrik Visser’t Hooft’s underground resistance in 1944, where she would perform at illegal events to raise funds for the cause.

In addition to dancing, Hepburn also delivered a newspaper by the resistance, known as the Oranjekrant. It was about the size of a paper napkin, as paper was in short supply, according the New York Post.

Hepburn was able to avoid suspicion, as she was just a teenager.

“Food was getting scarcer and scarcer… the Germans took everything” during Holland’s brutal “hunger winter.” More on her life during the Nazi occupation in @robertmatzen‘s Dutch Girl: Audrey Hepburn in WWII, out next week. #TCMParty pic.twitter.com/E5OvVZVJL4 — Sister Celluloid (@sistercelluloid) April 10, 2019

Having been educated in England when she was young, Hepburn also spoke English. Because of that, she also carried messages and food to Allied pilots shot out of the skies.

When she was 15, Hepburn’s family even harbored a downed English pilot, “hiding him in their house, much like Anne Frank,” according to the New York Post.

“My mother told me it was thrilling for her—it was risky, he was a stranger in uniform, a savior, and therefore a knight and hero,” Hepburn’s son, Luca Dotti said in the book, according to the New York Post. “Then I learned about the German law that if you were caught hiding an enemy, the whole family would be taken away.”

According to the New York Post, details of what happened to the pilot are scarce, but he was able to avoid German detection, and the Hepburns were never caught.

The Allied troops liberated her town when the war ended. However, when Hepburn and her mother rushed out of their home, they were met with guns pointed at them.

Hepburn quickly called out in English. The troops lowered their guns and cheered, with one soldier crying out, “Not only have we liberated a town, we have liberated an English girl!”

According to the New York Post, her son said, “The war was very, very important to her. It made her who she was.”