The Marauders introduce themselves to some Morlocks before killing them. One of the Morlocks attempts to attack them but Scrambler touches him, which disrupts the Morlock‘s invulnerability before Scalphunter shoots him. Cybelle, a young female Morlock, secretes acid for sweat and uses this to escape through a wall before attempting to get help from her fellow Morlocks. Arclight destroys the wall and harpoon throws an energy spear at the young woman, killing her. Callisto screams the girl's name, before challenging the Marauders. Vertigo uses her power on them to disorientate the underground community whilst Arclight causes a shockwave by hitting the floor. Around the corner the Morlock Piper uses his power to call for help from the various sewer animals.
Meanwhile at the Xavier estate, Dani Moonstar is washing her stallion as Colossus and Rogue put bails of hay into a barn. Logan offers to help but they tell him he needs to rest. Reluctantly he leaves. Colossus thinks that something is bothering Logan. In the kitchen Kitty is making a snack. Magneto tells her not to ruin her appetite but Kitty needs to pass her exams to keep her parents happy so she needs the extra energy. Kitty phases through the ceiling into Illyana's room, where they have a food break.
Wolverine is walking across the grounds when Kurt teleports in to surprise him. However Kurt falls into Logan's arms because he is still to weak to ‘port properly. They decide to go drink beer when the ground opens up and a giant Morlock creature tells them they are in trouble before collapsing.
In the infirmary, the Morlock‘s body is covered as the nurse tells the X-men about his fatal injuries. Psylocke tells the team that in his dying memory she saw super-beings killing everyone in the Morlock tunnels. Storm decides that the X-Men should help but Magneto should stay behind to look after the New Mutants; reluctantly he accepts.
Illyana teleports the team to the tunnels where they see lots of dead bodies. They find Callisto barely alive. They are just about to look for other survivors when they are attacked by Vertigo. She uses her mutant power to confuse them as Riptide fires throwing stars and spikes at them. Colossus and Rogue protect the others whilst Nightcrawler teleports to knock Vertigo unconscious. However Kurt has pushed himself too far with his attack, and is unable to save himself from Riptide spinning around his body. Riptide then picks up vertigo and runs away. The X-Men check on Kurt, who is badly injured. Wolverine is upset, but is able to pick up the scent of the Marauders so that they can follow. Storm tells Illyana to take the wounded back to the mansion, but not to come back to the tunnels with any reinforcements. Illyana decides to go back via Muir Island so that Moira Mactaggert can help with the wounded.
Elsewhere Scalphunter finds Annalee with two children. He opens fire on them all. Colossus and Shadowcat hear the gunshot and head in its direction. Colossus picks up a rock and throws it at Arclight and Scalphunter, but Arclight is just able to shatter it before it hits them. She then punches Colossus through a wall. Scalphunter puts his gun to Shadowcat's head but she phases and the bullets pass through her head without effect. He tries to stab her but is unable to hit her. Shadowcat decides to help Colossus than stay and fight.
The rest of the X-Men and a small band of Morlocks are walking through the tunnels towards the mansion when Wolverine suddenly knocks Storm to the ground as an optic blast narrowly misses her. At the far end of a long tunnel, they see the original X-Men, but before they can contact them, an explosion causes the tunnel between them to be blocked. (Arclight causes the cave-in in X-Factor #10). Colossus and Shadowcat meet with the group and also brought along the two kids and Annalee, yet her injuries are to extent and she dies in Callisto’s arms.
Scrambler, Riptide and Harpoon suddenly attack the X-Men. Harpoon attacks Wolverine, whilst Scrambler attempts to negate Storms powers. However he doesn't realize that she has already lost her power, and with the help of Callisto, Storm beats him up. Riptide fires his stars and spikes and many of the Morlocks are hit and killed. Colossus gets hit by one of harpoon's energy spears, and he feels like his insides are on fire. Scrambler touches Rogue but their powers neutralize each other, knocking them both out. Harpoon tries to take advantage and throws a spear at Rogue. Shadowcat dives at Rogue and phases with her to try and save her from the spear. Yewt instead of simply passing through her, Kitty screams in agony, and Colossus attacks Riptide in anger. He is overwhelmed by what he has seen and snaps Riptide's neck, killing him. Rogue can't believe what Colossus has done. Storm tries to help Kitty to her feet but she is not able to unphase, she tries her best but is stuck like a ghost. Storm decides that the X-Men and Morlocks should return to the mansion to patch up the injured, whilst Wolverine is to capture one of the Marauders for questioning so that they can find out more about their new enemies. She tells Wolverine that he can do what he likes with the rest of them.