On the series premiere, the Harris family is split up when a huge sinkhole opens in Los Angeles; Eve and her son end up in a primeval world.
Eve and Ty venture into the forest on a risky hunting expedition; Gavin must put his faith in the hands of an old friend.
Eve navigates the dangerous wilderness in order to save Josh; Gavin and Izzy work to prove survivors are alive inside the sinkhole.
With time running out before their window home closes, the survivors hatch a final escape attempt, forcing Eve to make an impossible choice.
When a superstorm hits the clearing, a structural collapse puts Marybeth and Lucas in danger; Gavin embarks on a journey into his past.