Terrifying earthquakes are only the prelude to an earth-shattering eruption in this disaster thriller by the acclaimed author of Powerless.

At Yellowstone National Park, earthquake tremors are common. But today, park scientist Tucker Mayfield detects something different: a disturbing new increase in activity and intensity. Lurking beneath the park, earth's largest supervolcano is beginning to awaken . . .

Racing against time, Mayfield mobilizes a team to evacuate all visitors from the park-including his family at the Old Faithful Inn. But when the earthquakes intensify, and the death toll rises, a shockwave of panic spreads across the nation. Troops are deployed and emergency plans are activated. But nothing can stop a natural disaster of this magnitude. When the volcano erupts, doomsday begins-and no one gets out alive . . .