Reed és Caitlin Strucker tipikus középosztálybeli szülők, akik a családfenntartás megszokott nehézségeivel küszködnek. Ám amikor kamaszkorú gyermekeik, Lauren és Andy bajba kerülnek a középiskolában, és kiderül róluk, hogy mutánsok, minden tőlük telhetőt megtesznek megóvásuk érdekében.

Miután Blink túlzottan megerőlteti magát, sokkos állapotba kerül, így Caitlin és Eclipse kénytelen felkutatni egy különleges szérumot, amely segítheti a felépülését. Mindeközben Reednek nehéz döntéssel kell szembenéznie, hiszen családja segítségre szorul, Polaris pedig bajba kerül.

Reed újra látni akarja a családját, így megállapodást köt a kormányszervekkel, Caitlin és a gyerekek pedig a létesítményen kívül keresnek segítséget. Mindeközben Thunderbird megtanítja Blinknek, hogy miként uralhatja képességeit.

Amikor a mutánsok kidolgoznak egy tervet az Őrszem Szolgálat tönkretételére, Eclipse felkeres egy régi barátot a sötét múltjából, hogy hasznos információkat szerezzen tőle. Mindeközben Lauren és Andy megpróbálják egyesíteni erőiket a csoport megsegítése érdekében.

Jace egy tragikus emlék hatására az Őrszem Szolgálat minden erejét beveti a földalatti mutánsok megtalálása érdekében. Mindeközben Blink élénk álmai egy új mutánshoz vezetik őt.

Thunderbird eltökéli, hogy kideríti, mit tett az Őrszem Szolgálat egy régi barátjával, és küldetésre indul a válasz megtalálása érdekében. Mindeközben Lauren egy új, hasznos képességekkel rendelkező baráttal találkozik, Blink pedig komoly döntést hoz a jövőjével kapcsolatban.

Eclipse-t felhívja régi szerelme, Carmen, így a férfi kénytelen utazást tenni sötét múltjában, hogy megvédje társait. Reed és Sage átnéznek néhány megszerzett titkosított aktát, és aggasztó részleteket tudnak meg Lauren új barátjáról. Mindeközben Thunderbird segít Blinknek a múltjáról beszélni, Jace pedig zöld utat ad egy speciális megfigyelési programnak Dr. Campbell segítségével.

Egyre több menekült érkezik a mutánsokhoz, de a csapat váratlan veszéllyel szembesül, amikor az egyik jövevényről kiderül, hogy az Őrszem Szolgálat kémje. Mindeközben Reed meglátogatja rég nem látott édesapját, és kiderül, hogy a családi titkok még hasznosnak bizonyulhatnak.

A csapat kidolgoz egy tervet az Őrszem Szolgálat fogságában lévő mutánsok kiszabadítására.

A morális válaszúthoz érkező Jace kénytelen valami nagyon értékeset átadni Dr. Campbellnek. A csapat a mutánsok főhadiszállásán nem tudja eldönteni, hogy mitévő legyen, ezért Reed és Caitlin saját kezébe veszi az irányítást.

A feszültség egyre nő a mutánsok főhadiszállásán, Reed családja biztonsága miatt aggódik, és ezért mérlegeli a lehetőségeit a létesítményben, Dr. Campbell egy továbbfejlesztett programot ajánl Jace-nek, amely mindent megváltoztathat.

Dr. Campbell elmegy egy mutánsellenes gyűlésre, mert országos szinten is ki akarja terjeszteni a programját, a mutánsok bázisán néhány csapattag veszélyes küldetésre indul, hogy megállítsák őt, Polaris többet tud meg a múltjáról, a központot pedig megtámadják.

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.

Thunderbird contacts a mutant lawyer who recruited him to the Underground years ago, hoping she can help him find the Inner Circle. Lauren and Andy have a shared dream, which distracts Andy from his training and prompts Reeva to consider cutting her losses with him, which, in turn, makes Andy second-guess his separation from his sister. Meanwhile, Reed must keep a huge secret from the group and Jace picks up the mutants' trail again

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.

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 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.

With the Inner Circle and the Purifiers on the rise, and the nation more divided than ever, the dream of the X-Men is on the verge of failure. In attempts to revive the Mutant Underground, Evangeline proposes a country-wide meeting. Meanwhile, Lauren and Andy continue to disagree in their dreams and the Frost Sisters attempt to intervene. Caitlin makes the risky suggestion of connecting with a family member for vital intel, and Lorna tries to secretly investigate Reeva's plans for the Inner Circle.

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.

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.