The White House grapples with a mysterious biological threat. Their only hope is to crack Sophia during interrogation. Meanwhile, Vicky and Carter keep their hostage captive while they await further instructions. FBI Agent Collier, on her search for Leila, stumbles upon Vicky's secret life. Elsewhere, a powerful businessman, Dempsey with classified intelligence and ties to the White House, emerges from the shadows.

Sophia's suspicions are confirmed when Thomas reveals a shocking new plan. Leila and Sean battle mercenaries while searching for Samantha.

Negotiations for the release of the Sleepers begin after Sophia triggers a national disaster; Sean and Vicky continue their mission.

With doubt still surrounding the tragedy at the White House, Sterling encounters an unlikely ally in Simon, who risks his life to return with a possible antidote. Against the wishes of Chief of Staff Richard Peel, Jarvis authorizes an air strike to neutralize them. Meanwhile, Sophia continues on her diabolical plan to exterminate the human race, now with the help of an unwitting accomplice -- Leila