The Last Horizon is a gripping and deeply investigative account of one of the most haunting aviation disasters in history. In 1979, Air New Zealand Flight 901 flew calmly into Mount Erebus in Antarctica, killing all 257 people on board. It was not a story of mechanical failure or pilot panic, but of something far more unsettling, a fully functioning aircraft, a confident crew, and a fatal error hidden inside a system that appeared routine. Scarlett Dawson reconstructs the disaster with precision and atmosphere, revealing how a small change in flight coordinates, made on the ground and never clearly communicated, placed the aircraft directly in the path of the mountain. In the strange visual conditions of Antarctica, where light erases depth and distance, the crew believed they were flying safely over open terrain. What followed was not only a catastrophic impact, but a prolonged and bitter struggle over responsibility, truth, and institutional accountability. More than a disaster narrative, this book explores how modern systems fail quietly and how organizations respond when those failures are exposed. Through courtroom battles, conflicting reports, and decades of unresolved tension, The Last Horizon shows that the tragedy of Erebus did not end at the moment of impact, it continued in the fight over who would be held accountable and who would carry the blame.