The White House is rocked by the sudden illness of one of their own, leaving Chief of Staff Peel and Sterling to investigate possible conspirators. Michael Buchanan comes to the aid of Leila, but it leaves them both at risk of Sophia's wrath. Across the globe in Russia, Sean and Vicky race to stop Sophia's weapon from being loaded onto a plane heading to the United States.

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. Elsewhere, Sean and Vicky try to prevent the deaths of many thousands of innocent people.