Tom leads the search for Rachael, as her situation becomes increasingly dire; Maggie and Dr. Ward make a series of unexpected discoveries.

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

Bellamy ends up waking up alone on the outskirts of Arcadia, unable to remember the events of the last seven days.

Bellamy looks for help from a surprising source. Another disappearance results in a quest for answers.