Princess Diana captured the world's imagination, so much so, many thought they really knew her. The reality is, they just knew a part of the Diana story. CBS News explores the public and private life of a complex woman and the lingering questions surrounding her death. 

"Her name was Diana and the world fell in love with her," "CBS This Morning" co-host Gayle King says in "Princess Diana: Her Life | Her Death | The Truth" airing Monday at 8/7c on CBS. "But her fairy tale life also had a heartache – it did not have a happily ever after ending."

This summer it will be 20 years since the death of Diana, Princess of Wales. To mark the anniversary, King anchors the broadcast from Althorp, the princes

s's family estate in England. Through the words of those who knew her, who admired her, in her own words, and through the rich archive of CBS News, the special looks at the impact Princess Diana had on Britain, the monarchy and the world and features interviews with close friends who open up about their personal conversations Princess Diana in the weeks leading up to her death. In fact, friend Lana Marks reveals something surprising -- the man who was the only one true love of her life.

From her wedding to Prince Charles in 1981 until her tragic death on Aug. 31, 1997 in a horrific car crash in the Pont de I'Alma road tunnel in Paris, Princess Diana was a public draw, but there was much more behind the headlines most people never knew.

"I think Diana's death robbed the world of an extraordinary, luminous character," says author Patrick Jephson. "She leaves an unfillable gap on the world stage."

Behind the crown and the designer dresses, Diana was a complicated and occasionally unpredictable woman, say those who knew her best.  "She always said, 'I want to be normal,'" says Ken Wharfe, her former bodyguard. "The tragedy is, with being a member of the royal family, it's almost impossible to be normal."

She was far from normal. In fact, the marriage that captured the hearts of people around the world was a struggle. In public they played their parts, but in private it was a different story. They would fight, says author Sally Bedell Smith, and she would taunt Prince Charles by telling him he'd never be king.

"And there was one moment when they were having a big fight, and he was down on his knees praying, and Diana was hitting him even as he was praying," Bedell Smith says. "That was the kind of intensity of the discord that they had."

Just as the world watched as Prince Charles and Diana married, they watched as the marriage unraveled. They also followed along as Princess Diana reemerged in public life alone after the divorce and right up until she died. At the time, the summer of 1997 was supposed to be a time of self-discovery and new beginnings. She was no longer a member of the royal family and was dating businessman Dodi Al Fayed. It all ended when they piled into a Mercedes and sped off from the Ritz hotel in Paris with paparazzi chasing them.

When the Mercedes reached the Pont de I'Alma road tunnel, driver Henri Paul lost control. He sideswiped a slower moving white Fiat that drove off.

Her death was just as controversial as her life. Almost immediately conspiracy theories were raised about what happened. Were the paparazzi somehow responsible? Had someone tampered with the Mercedes? What about that white Fiat? Did the driver intentionally cause the crash? And what could have been done to prevent the crash?

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