“This particular phase in my life is the most dangerous. My husband is planning ‘an accident’ in my car, brake failure and serious head injury in order to make the path clear for him to marry.” —Letter written by Princess Diana, late 1996

It is a moment that remains frozen in history. When the Mercedes carrying Diana, Princess of Wales, spun fatally out of control in the Pont de l’Alma tunnel in Paris in August 1997, the world was shocked by what appeared to be a terrible accident.

But two decades later, the circumstances surrounding what really happened that night—and, crucially, why it happened—remain mired in suspicion, controversy, and misinformation. Until now. Dylan Howard has re-examined all of the evidence surrounding Diana’s death—official documents, eyewitness testimony and Diana’s own private journals—as well as amassing dozens of new interviews with investigators, witnesses, and those closest to the princess to ask one very simple question: Was the death of Princess Diana a tragedy…or treason?

Diana: Case Solved has uncovered in unprecedented detail just how much of a threat Diana became to the establishment. In these pages you will learn of the covert diaries and recordings she made, logging the Windsors’ most intimate secrets and hidden scandals as a desperate kind of insurance policy. You will learn how the royals were not the only powerful enemies she made, as her ground-breaking campaigns against AIDS and landmines drew admiration from the public, but also enmity from powerful establishment figures including international arms dealers, the British and American governments, and the MI6 and the CIA.

And, in a dramatic return to the Parisian streets where she met her fate, the two questions that have plagued investigators for over twenty years will finally be answered: Why was Diana being driven in a car previously written off as a death trap? And who was really behind the wheel of the mysterious white Fiat at the scene of the crash?