Amy and a wounded Brad seek refuge with Brad's ex-military instructor; Dr. Lear reflects on the decisions that led him to involve Fanning in his research; testing of the virus on Anthony Carter begins.
Brad makes a deal with Sykes and Richards to stay with Amy at Project NOAH as they begin testing the virus on her, then forms an alliance when he discovers the truth about the state of the inmates in 4B; Babcock sheds light on her past.
Wolgast convinces Sykes and Lear to let him and Amy outside of the facility for exercise in an effort to protect her; Fanning's hold on those kept in Project Noah grows stronger as flashbacks reveal how Carter wound up on death row.
Guilder and Richards race to mobilize a search party when a viral gets loose outside Project NOAH; Amy creates friction with Brad when she volunteers to help in an unexpected way.
Brad and Amy plot their escape with an unlikely accomplice when a high ranking official suddenly arrives at Project NOAH. Sykes and Richards begin questioning each other's motives.
Brad and Lila remember their history together as they plan to save Amy; Horace Guilder is given full authority over Project NOAH; Carter prepares Amy for Fanning's grand plan; Lear fights to help Elizabeth.
As Amy experiences symptoms of the virus that indicate she is close to turning, Brad brings everyone together, and Lila and Sykes race to perfect an anti-viral medicine to save her from Fanning.
Amy must decide what's best for humanity when the only way to stop Fanning and the virals from escaping Project NOAH involves an explosion that could leave Brad, Sykes, and the cure for the virus in the crossfire.
