Polaris' baby begins to suffer from a deadly illness, leaving the Inner Circle unable to heal her, and prompting them to turn to an unexpected source for help. Meanwhile, Reed and Lauren take an excursion to deliver illegal meds, but Reed's powers complicate their plans. Then, Thunderbird and Blink meet the leader of the Morlocks - a shadowy group of mutants that live underground - who offers to help them find the Inner Circle, but the two factions may not have the same goals.

The Struckers, minus Andy, begin to rebuild their broken trust, while Thunderbird, Blink and Eclipse visit Wire, hoping to convince him to help again. But when they get there, they learn that something terrible has happened from Wire's brother, Graph. The team discovers that the Inner Circle is on the way to raid a mutant detention facility, so they make moves to try to intercept them. Meanwhile, Jace is contacted by a member of the Purifiers.

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.

Tensions within the Inner Circle are at an all-time high, as Andy comes to Rebecca's defense against Reeva. After making an important discovery about Dr. Risman's research, Lauren convinces Reed and Caitlin that they must take action to destroy it. Frustrated with not being taken seriously, Jace begins to strategize with the Purifiers. Meanwhile, the Mutant Underground continues to work on saving mutants. However, tensions flare between Blink and Thunderbird as they confront their differences.

The Mutant Underground wrestles with the idea of recruiting the Inner Circle to assist them. Andy considers reconnecting with his family when he learns about his father's powers, but Lauren may not be as willing to have him back as their parents. Find out if the Mutant Underground and Inner Circle will be able to put their differences aside in order to save John from 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.

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.