The White House is gripped by a power struggle of historic proportions, pitting Martinez (Blair Underwood) and Chief of Staff Peel (guest star Roger Bart, "Desperate Housewives") against Jarvis (Bill Smitrovich) and his secret ally, Sophia (Laura Innes). Elsewhere, Sean (Jason Ritter), Vicky (Taylor Cole), Sterling (Zeljko Ivanek), and Simon (Ian Anthony Dale) race to stop the dispersion points for the virus. Meanwhile, Leila (Sarah Roemer) fights for her life. But it all may be too late -- as the portal begins to open, sending tremors across the globe. Lisa Vidal also stars.