The Strucker family have their normal lives changed when the children, Lauren and Andy, have their powers revealed to the public. Facing prosecution from a sinister organization, Sentinel Services, they choose to become fugitives and end up joining up with a refugee group, the Mutant Underground. Now, they must grapple, as a fully-fledged family, with those who fear them, while also dealing with problems that lie within their newfound home.
After the explosive events of last season, the lingering threat of mutant haters is still out there. However, the reintroduction of the Hellfire Club has created a schism in the Mutant Underground, with certain members becoming seduced by the former group's motives. Now, history has repeated itself, as the two groups not only contend with the authorities, but also against the opposing side.