When northern communist forces seized control of South Vietnam on April 30, 1975, ending the war, life became tough.

After four decades, Phuc, now a mother of two sons, can finally look at the picture of herself running naked and understand why it remains so powerful. It had saved her, tested her and ultimately freed her

Medical treatment and painkillers were expensive and hard to find for teenager Kim Phuc, who still suffered extreme headaches and pain.

She worked hard and was accepted into medical school to pursue her dream of becoming a doctor.

But all that ended once the new communist leaders realised the propaganda value of the “napalm girl” in the photo.

She was forced to leave college and return to her home province, where she was trotted out to meet foreign journalists. The visits were monitored and controlled, her words scripted. She smiled and played her role but the rage inside began to build and consume her.

“I wanted to escape that picture,” she said. “I got burned by napalm, and I became a victim of war... but growing up then, I became another kind of victim.”

She turned to Cao Dai, her Vietnamese religion, for answers. But they didn’t come.

“My heart was exactly like a black coffee cup,” she said. “I wished I died in that attack with my cousin, with my South Vietnamese soldiers. I wish I died at that time so I won’t suffer like that anymore ... it was so hard for me to carry all that burden with that hatred, with that anger and bitterness.”

One day, while visiting a library, Phuc found a Bible. For the first time, she started believing her life had a plan.

Then suddenly, once again, the photo that had given her unwanted fame brought opportunity.

She travelled to West Germany in 1982 for medical care with the help of a foreign journalist. Later, Vietnam’s Prime Minister, also touched by her story, made arrangements for her to study in Cuba. She was finally free from the minders and reporters hounding her at home but her life was far from normal.

Photographer Nick Ut, then working at the AP in Los Angeles, travelled to meet her in 1989, but they never had a moment alone. There was no way for him to know she desperately wanted his help again.

“I knew in my dream that one day Uncle Ut could help me to have freedom,” said Phuc, referring to him by an affectionate Vietnamese term. “But I was in Cuba. I was really disappointed because I couldn’t contact with him.”

While at school, Phuc met a young Vietnamese man.

She had never believed anyone would ever want her because of the ugly patchwork of scars that banded across her back and pitted her arm, but Bui Huy Toan seemed to love her more because of them.

The two decided to marry in 1992 and honeymoon in Moscow. On the flight back to Cuba, the newlyweds defected during a refuelling stop in Canada. She was free. Phuc contacted Mr Ut to share the news and he encouraged her to tell her story to the world. But she was done giving interviews and posing for photos.

“I have a husband and a new life and want to be normal like everyone else,” she said.

The media eventually found Phuc living near Toronto, and she decided she needed to take control of her story.

A book was written in 1999 and a documentary came out, at last the way she wanted it told.

She was asked to become a UN Goodwill Ambassador to help victims of war. She and Ut have since reunited many times to tell their story, even travelling to London to meet the Queen.

“Today, I’m so happy I helped Kim,” said Ut, who still works for AP and recently returned to Trang Bang village. “I call her my daughter.” After four decades, Phuc, now a mother of two sons, can finally look at the picture of herself running naked and understand why it remains so powerful. It had saved her, tested her and ultimately freed her.

“Most of the people, they know my picture but there’s very few that know about my life,” she said.

“I’m so thankful that ... I can accept the picture as a powerful gift. Then it is my choice. Then I can work with it for peace.”