Margaret convinces Lucille to host a dinner to celebrate Jacob's return, but unexpected guests strain relations in the Langston family to the breaking point. Meanwhile, Bellamy continues to research the history of the mysterious bones, and Rachael receives unsettling news about her baby.

Rachael refuses to accept any treatment for the virus as she is concerned for the safety of her unborn child. Elaine's brother Ray comes down with the disease.

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