A traitor in the battle threatens the efforts of the X-Men and the Brotherhood against Magneto, who has another secret weapon -- the Sentinel robot.

The battle against Apocalypse rages as X-Men, the Brotherhood, and Acolytes join forces to stop him from turning all humans into mutants.

As all the monsters in the tomb attack, the teammates fight to survive and find a way out.

Rogue begins to lose control of all the people she's ever absorbed as they fight to take over. She discovers unsettling information about Mystique. Scott and Jean go on a date... or do they?

Xavier finds Apocalypse in Egypt, and Apocalypse unleashes four horsemen, who battle the X-Men.

At Xavier's urging, the Brotherhood and the X-Men unite to battle Magneto; and the Institute begins to self-destruct while students are trapped in the mansion.

X-Men and the Brotherhood deal with the aftermath of the world finding out about mutants. The Institute is blown up, and Mystique posed as Prof. X to blow it up. Some of the X-Men and Brotherhood are captured, leaving the mutants that escaped to find them and the Professor.

Rogue and Wolverine duck a squad of soldiers when the nationwide alert goes out against mutants, while Storm and Beast go into a meeting of Congress to defend themselves. Meanwhile Juggernaut goes on a rampage and the X-Men feel obliged to take him down.

As Jean's and Scott's graduation day approaches, Rogue suddenly leaves the mansion.

Scott and Rogue end up on a geology club field trip together. Scott tries to be friendly to her, but it turns out Mystique has other plans...

Magneto reveals the his plans for the winners of his challenge - to fully unlock their powers with a machine he has built. Back at the mansion, those left behind regroup, and decide to pay Magneto a little visit.

Magneto steals plans for a top-secret project that produced super soldiers. Wolverine worked on it during World War II.

Mystique frees a mutant called the Scarlet Witch from an asylum, hoping she'll help the Brotherhood, but Mystique doesn't know the witch is seeking revenge on Quicksilver and Magneto.

Mesmero mentally controls Gambit into stealing half of the Spider Stone from Angel.

A mysterious female assassin terrorizes the X-Mansion, knocking out the X-Men one by one. Wolverine finds out that it is his clone, created by the Dr. Deborah Risman and raised without love by HYDRA, and she wants to kill him because she holds him responsible for her miserable life. Wolverine and X-23, as she is called, square off in a battle that Wolverine does not want to win.

Rogue's nightmares seem to show images from Kurt's past, but in them he's far too young to remember. So where did they come from?

As mysterious metal pods appear, picking up the mutants one at a time, Cerebro detects a new mutant in Hawaii: Alex Summers - Scott's believed to be deceased brother.

The X-Men pursue Apocalypse in Mexico, hoping to find and overcome him before Magneto finds him.

After being kept in the dark about her powers for years, a young female mutant touches a fellow student and absorbs his strength, his memories - his life. Afraid and confused, and unable to differentiate her memories from the absorbed ones she runs away - straight in to the hands of Mystique.

Jean's telepathy changes, arriving in surges she can't control; and Hank McCoy joins the faculty as a science-and-gym teacher.

Xavier suspects that a flying "angel" seen above New York is a mutant, and he sends Cyclops and Rogue to find him before Magneto does.

While the X-Men are at a summer camp, learning survival training, Mystique releases Cain Marko - the unstoppable Juggernaut - in hopes of getting his help in obtaining Xavier's mutant location system.

Jean is possessed by a mutant with telepathic powers, which he uses to control the students and have them help him in his plot to release the imprisoned Apocalypse, a mutant who wishes to enslave the human race.

During the rebuilding of the manor, Kitty and Kurt intercept a bunch of graffiti artists disguised as monsters. The older students get to go back to Bayville High for one day before attending a hearing to determine their ultimate fate, while they are banned from using their powers.

Mystique escapes from imprisonment while the X-Men repair and rebuild the Institute. Disguised as Alex, she lures Scott into a trap - leaving him stranded in the middle of the Mexican desert without his glasses.