Bellamy and Sheriff Fred try to find Caleb; Maggie gives Jacob a checkup; Pastor Tom's old love returns.

The return of the dead reaches critical mass, sending the town into chaos; Sheriff Fred implements his own agenda, triggering an unexpected siege.

The death a beloved member of the community leaves Arcadians in mourning whilst a cure for the virus is provided by stem cells from Rachael's baby.

Jacob and Margaret go missing during a violent storm that knocks out the power; another visitor arrives.