The journey through the rift becomes even rockier as the survivors are forced to take to the water, crossing a vast deepwater basin on improvised boats. To make it, Molly and the others must work together, but a rift of a different kind is forming among the survivors. If they aren't careful, it could eat them alive.

Brianna Dobson has been chosen to work with world-renowned geologist Dr. Grier in Yellowstone National Park for the summer, and she couldn't be more excited! But then Dr. Grier tells her and the other kids on the project the real reason she's invited them to Yellowstone: A massive supervolcano in the park is about to erupt-and if they can't stop it, Earth will be plunged into an endless winter, and civilization will be destroyed. Bri and her new...