After an emotional reunion, Gavin and Eve attempt a daring escape from their unforgiving captors; Lucas leads a dangerous mission to the fort to reclaim the resources his friends so desperately need.

Eve, Gavin and others attempt to commandeer a shipment of black rock to gain access to the mysterious Building, where they believe they may find a way to bring Josh and Riley home. In 1988, Josh and Riley must act swiftly to prevent Caroline from altering the timeline.

Gavin leads the survivors in trying to find Eve, Josh and Riley. Will he be able to finally reunite his family and still find a way back to the lives they once knew?