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?