It was one the most beautiful mountains in America: Mt. St. Helens in Washington State. But what many didn't know was that this peaceful mountain had an explosive past. For more than a century, it had been quiet. But belowground, pressure had been building, and soon, kaboom! Mt. St. Helens would erupt with terrifying fury.

Although 11-year-old Sally Tanner knew the mountain well, she never imagined that this serene wilderness could turn deadly. Then, on May 10, 1980, she found herself face-to-face with one of nature's most devastating forces, and her knowledge of Mt. St. Helens was the only thing that could keep her alive.