The Mutant Underground rescues a girl from a Sentinel raid, but fails to save her family; Eclipse and Caitlin get info on the Inner Circle with help from a criminal hacker; Polaris prepares for her baby's birth.
Thunderbird hopes a mutant lawyer who recruited him to the Underground can help find the Inner Circle; Andy and Lauren have a shared dream; Reed must keep a secret from the group; Jace is back on the mutants' trail.
As Caitlin and Thunderbird struggle to save the life of a mutant injured in the Inner Circle's chaotic liberation of a psychiatric hospital, they discover clues to the identity of the powerful mutant Polaris and Andy were sent to retrieve. Meanwhile, as Jace joins up with the Purifiers to chase down the escaped mutants, he comes dangerously close to colliding once again with the Mutant Underground.
The Inner Circle prepares for a secret ambush, but Polaris is reluctant to join and Reeva tasks Esme with getting Polaris on board. Esme confides in Polaris, revealing her and her sisters' troublesome past. Meanwhile, Thunderbird trains Reed on controlling his powers and The Purifiers attack The Mutant Underground as they attempt to rescue a group of homeless mutants.
Reeva reveals her plans for a major mission for the Inner Circle to secure some needed funds. Meanwhile, the Mutant Underground must contend with Reed's unstable powers, hoping that some medical help from Caitlin and Lauren will keep his destruction in check. Also, Jace is introduced to Benedict Ryan, a well-connected public figure who supports the efforts of the Purifers, but the two may not see eye-to-eye. Then, Thunderbird finally confronts Blink about her dealings with Urg, after weeks of tension over their meeting.
In attempts to stabilize Reed's powers, Reed, Caitlin and Lauren meet with Dr. Risman, a doctor who treats patients with debilitating X genes. However, Lauren finds out Dr. Risman is not who she thought she was. Following the Inner Circle's bank ambush, Thunderbird and Blink continue to work together to chase them down. Meanwhile, Polaris reflects on her troubled relationship with her father and takes steps to protect Dawn from the Inner Circle.
Tensions are rising within the Inner Circle as Andy defends Rebecca against Reeva's treatment. Lauren tries to convince her parents to destroy Dr. Risman's research. A frustrated Jace works with the Purifiers.
Reed worries as Lauren becomes intrigued by her ancestors and their violent powers. Lorna begins to reevaluate her trust in the Inner Circle after figuring out the past of Reeva's new trainees. Meanwhile, Benedict Ryan continues to encourage Jace to take action with the Purifiers. Marcos asks Clarice to go to the Morlocks in search of information on the Inner Circle and Thunderbird gets a call from Evangeline.
Lauren stops sleeping so she can avoid the forces in her dreams pushing her towards joining Andy and giving in to her dark side. Glow is in trouble after being shot by the Purifiers, and Blink convinces the Morlocks to let Caitlin save Glow. Meanwhile, Polaris learns the details of what Reeva is planning, and Reed helps Lauren fight off her dreams.
When one of the Inner Circle goes missing, Reeva intensifies security in their compound, but realizes that her plans may have already been exposed. Furious and paranoid, Reeva resorts to violence. Caitlin and Reed consider using the serum to restrict Lauren's use of her powers, hoping it will help her as she wrestles with nightmares about the Inner Circle and her ancestors. And it's the battle of two extreme ideologies when the Morlocks and the Purifiers come face-to-face in battle.
Lauren can't access her powers when it matters most, leaving Caitlin to take matters into her own hands when they are being pursued. Reeva finally reveals her plan for the Inner Circle and it's darker than anyone could have imagined. Meanwhile, Jace confronts some regrets about his actions and is torn between pressures from the Purifiers and his own beliefs.