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.

The White House is gripped by a power struggle of historic proportions, pitting Martinez and Chief of Staff Peel against Jarvis and his secret ally, Sophia. Elsewhere, Sean, Vicky, Sterling, and Simon race to stop the dispersion points for the virus. Meanwhile, Leila fights for her life. But it all may be too late -- as the portal begins to open, sending tremors across the globe.