Kiera battles old friends by allying with former enemies. Alec stands on the precipice of power with one man in his way.

Nicholas reveals a shocking secret while in a pill-induced haze. Rosie wants to save Kenneth. Zoila forces Genevieve to face her mother. Valentina asks Remi to help Ethan. Spence gets some bad news.

On the outskirts of Charleston, just steps away from perceived safety, The Mason Clan and the remaining 2nd Mass suddenly find themselves under brutal attack by a new Espheni war machine – and a new, deadly creation unlike anything previously encountered. Divided like chattel and spread to the winds, The Masons must each forge new relationships and abilities to survive.

As Cameron nears completion of the BIOS, a crisis threatens the project's future and requires all hands on deck to save the machine.

Walt and the team track missing teenage campers on a leadership trip in the wilderness; Branch continues his unauthorized search for his shooter.

Increase gets closer to understanding who really runs Salem. Anne finds herself in danger, and Mr. and Mrs. Hale realize that Alden may be the only one who can save her.

Captain Tom Chandler and the crew of the USS Nathan James set out for the Arctic with two civilian virologists, Dr. Rachel Scott and Dr. Quincy Tophet, who claim to be studying birds. When they come under attack by a renegade team of Russian forces, Chandler learns these virologists are actually collecting samples of the source of a deadly virus that has wiped out over half the human population while they've been at sea. As they head home on the orders of the remaining U.S. government, Chandler and his crew realize that home is a shadow of what they left, and the safest place to develop a vaccine for this deadly disease is out at sea on their ship.