With the sudden arrival of a high ranking official, Horace Guilder, to Project NOAH, Brad and Amy begin to strategize a possible escape plan with the help of an unlikely accomplice. Meanwhile, Sykes and Richards begin to question each other's motives, and a shaky past between Lear, Elizabeth and Fanning is revealed.

When the only way to stop Fanning and the virals' escape from Project NOAH involves a dangerous explosion that could leave Brad, Sykes, and the cure for the virus caught in the crossfire, Amy must be the one to decide what's best for humanity. In the wake of this, surprising alliances form and a key figure returns to instill confidence, convincing everyone to fight for their lives.