As Polaris and Andy join the Hellfire club, search heats up for the two as the Underground tries to get intel on the new Inner Circle.
As Caitlin and Reed try to balance the search for Andy and the attempt to help Lauren with her trauma, the connection between the two siblings proves threatening to the Inner Circle.
As Reed's manifesting powers threaten to put the family in peril, Clarice is offered a bargain as she tries to get more information from a mutant group known as the Morlocks.
As the Underground gains info on the Inner Circle's next move, a confrontation turns the tide in favor of mutants, but the showdown between the Underground and the Inner Circle leaves Lauren devastated.
As the Purifiers launch an attack to win the favor of the public, the Inner Circle pulls out all the stops to get a powerful mutant on their side.
As Jace sets a trap for the Underground, Reed's powers spiral out of control. Polaris gains an unexpected ally. Lauren and Caitlin learn of the extent of Rebecca's powers.
As the Inner Circle makes their move, Rebecca crosses a line that horrifies everyone involved in the attack. Clarice calls out the disorganization and aimlessness of the Underground, making a case for working with the Morlocks.
Polaris makes a tough call in order to protect Dawn. As the Struckers manage to find a way to stabilize Reed, Lauren is shocked when she learns of the connection between the Purifiers and a familiar face.
Dissension within the ranks of the Inner Circle ends on a bloody note. The Struckers face off against Madeline. Polaris and Andy make a move that frees all incarcerated mutants.
The Underground and the Inner Circle come to a tentative peace to achieve a common goal, but the Struckers are horrified to witness Andy's extremism.
After some new recruits shake Polaris's faith in the Inner Circle, she seeks to ally with the Underground to bring them down. Jace's profile grows in the media after he is hailed as a hero.
As the history behind the formation of the Morlocks and their link to the Underground is revealed, Polaris sends a warning to save the lives of the Underground leaders. The Frosts deceive Any and use him to lure Lauren in.
Erg battles his distrust of humans as he teams up with Caitlin and Clarice to help the life of one of their own. Reed intercepts the Frosts' attempt via Andy to turn Lauren, who takes drastic measures to avoid being tempted by power.
Jace is disillusioned after an attack by the Purifiers on the Morlocks reveals just how low they are prepared to sink in their attack on mutants. Polaris is devastated when her actions inadvertently lead to the murder of an innocent mutant.
As the Inner Circle prepares for their final move, Reed tries to reach out to Andy as Polaris reveals the truth to him. John tries to figure out if Clarice has died.
As the Inner Circle kidnaps Andy and Lauren, Reed carries out a risky plan that could claim his life to save them. A final confrontation between the Underground and the Inner Circle decides the fate of mutant leadership.