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.

With Josh's life on the line, Eve traverses the dangerous wilderness back to the clearing to save him; desperate to kickstart a rescue mission, Gavin and Izzy work to prove survivors are alive inside the sinkhole as government agents track them.

With the survivors' food supply dwindling, Eve and Ty venture into the forest on a risky hunting expedition; as an unlikely rescue mission comes to fruition, Gavin must put his faith -- and the fate of his family -- in the hands of an old friend.

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

Eve, Levi and the rest of the search party explore a mysterious fort that raises more questions than answers; with the help of a new ally, Gavin and Izzy embark on a dangerous and unauthorized mission to save their family despite government warnings.

With time running out before their window home closes, the survivors hatch a final escape attempt, but that plan is put into question when they receive a stark warning from Gavin that it will end in disaster, forcing Eve to make an impossible choice.