While Gavin enlists the help of his grandfather to guide him to his missing wife, Eve and Levi navigate a horrifying new reality. In 1988, Josh and Riley discover they’re being followed by a suspicious man who reveals information about the mystery behind the sinkholes.

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.

The Harrises return to 10,000 BC, determined to upload a virus that will stop all sinkholes, despite knowing that this will mean they will never get home again. An unlikely leader rallies the Clearing to face an oncoming prehistoric threat.

When a Survivor is murdered, Lucas and Sam lead a contentious investigation to find the killer. Gavin embarks on a mission to save Eve from the fateful vision he’s had of her death. Eve finds herself closer than ever to seeing it come true.

A ruthless enemy holds the Clearing captive, threatening to kill a beloved Survivor if their demands for an unexpected item aren't met. Gavin and Sam lead the rescue attempt, aided by an old friend whose return holds more questions than answers.