When a massive sinkhole opens in Los Angeles, the Harris family is split in two. Eve and her son are sent to a mysterious primeval world. Gavin discovers that the visions that have plagued him for years might hold the key to bringing them home.

The sight of a crashing plane spreads a wave of unexpected hope through the clearing as Eve and the other survivors search for its fallen pilot. Gavin and Izzy seek help from an unlikely source after the government permanently suspends their mission into the sinkhole.

When a chaotic superstorm hits the clearing, a structural collapse puts Marybeth and Lucas' lives in danger. Eve, still at odds with everyone, tries to make amends by leading the effort to dig them out. Gavin embarks on a journey into his past.

When a stunning revelation puts Josh and Izzy's lives on the line, Eve and the other survivors desperately search for the young boy who holds the key to saving them. Gavin and Izzy must rely on a stranger if there is any hope to reunite their family.