For more than 100 years, Mount St. Helens had been quiet, a beautiful mountain surrounded by forests. Hikers climbed its winding trails. Skiers raced down its snowy slopes. Children splashed in its crystal clear lakes.

Except this peaceful mountain was not a mountain.

It was a dangerous volcano, a deadly cone filled with molten rock and poisonous gases. And soon it would explode with the power of ten million tons of dynamite.

In the minutes before the eruption, eleven-year-old Jessie Marlowe and her best friends Eddie and Sam were in a forest near St. Helens. The day was warm and bright, the sky brilliant blue. St. Helens rose up over them, its perfect triangle peak sparkling with snow.

And then,

Kaboom!

Suddenly, Jess was in the middle of the deadliest volcanic eruption in American history.

She watched in horror as the sky turned pitch-black. A blizzard of ash poured down, swirling up her nose and making it almost impossible to breathe. Hot rocks pelted her like bullets shooting down from the sky.

Then, whoosh, a blast of wind exploded out of the mountain, a white-hot mix of ash and gas and shards of rock. It raced down the mountain at jet speeds, burning everything in its path. The heat hit Jess and the boys, knocking them down. Jess felt as though she would burst into flames. Every breath was like inhaling fire.

But the terror was just beginning.

The eruption had shattered the mountain, and now a fifty-mile-wide avalanche of rock and mud and melted ice was taking aim at the valley below. It grew larger by the second. It snatched up trees and boulders. It tore away bridges and swept away houses.

It would destroy everything — and everyone — in its path.