Ryan Hardy, Agent Mike Weston and FBI Specialist Debra Parker, who is brought in to lead the investigation into Joe Carroll and his followers, dive deeper into the history of Carroll's psyche. To do so, they enlist the help of Carroll's ex-wife, and Hardy's former love, Claire Matthews. Meanwhile, Emma, Jacob and Paul keep Claire's son Joey at a house in the country as they prepare for their next move

A new follower is found in Rick, who is on a determined path to follow through on Carroll's orders. Hardy and the FBI attempt to predict Rick's course of revenge, which leads to a surprising outcome. Meanwhile, Paul's jealousy over Emma and Jacob's relationship leads to a breaking point, and the origin of Hardy and Carroll's relationship.