A suburban couple is forced to flee from a hostile government after their teenage children begin to show they possess certain powers.

After exerting her powers beyond their limits, Blink goes into a state of shock, forcing Caitlin and Eclipse to go on a mission to find a special serum that will help her to recover. Meanwhile, Reed faces some difficult choices when it comes to helping his family, and Polaris runs into some trouble.

Polaris learns more about her past and makes a crucial decision that could have impactful consequences. Meanwhile, the Mutant HQ comes under attack and, with everything to lose, relationships are put to the test and alliances shift.

Reeva Payge purges the Inner Circle of those who disagree with her, leaving her completely in charge. Then, fast-forward six months, when the Mutant Underground saves a girl, but not her family, from a Sentinel raid. Against the group's wishes, Eclipse and Caitlin meet with a criminal hacker to get info on the Inner Circle. Meanwhile, Polaris prepares for the birth of her baby, her contractions magnetizing anything metal and wreaking havoc. She also makes Andy promise to save the baby, no matter what.

Reeva prepares to carry out her plan for the Inner Circle, but not everyone is on the same page. Reed struggles to manage his powers and the family realizes that without enough of the serum, it's only a matter of time before he completely loses control. Frustrated and egged on by Benedict Ryan, Jace and the Purifiers are on the attack, but for Jace, things aren't as black and white as they once were.