Uncanny X-Men #225, 226, 227
X-Factor #24, 25, 26

The Fall of the Mutants was different for both teams. For the X-Men, it began when the went to find Storm at Forge's Aerie in Dallas, the last place she had been seen. Things were starting to get strange when they arrived, Forge's Aerie gutted, and snow falling in the middle of summer. Freedom Force, led by Mystique, arrived on the scene shortly thereafter, and a battle between the two groups ensued. As things began to progress into weirdness, Indians, cavemen and demons alike beginning to appear, the two teams decided to join together to fight against this larger threat.

Meanwhile, Storm and Forge had been swept off to a virgin world of great beauty, effectively taken out of the battle by the Adversary, bringer of chaos, who was concocting a plot which he did not want them to be part of. On the other side of the X-Men's world, a beautiful woman appeared to Colossus, prompting him to call his sister, Illyana (Magik), to teleport to him and then take him to the X-Men. She did so and he arrived on the scene just in time to be thrust into the battle. The X-Men were slowly unraveling the mystery of the oddities occuring, entering a prehistoric jungle which had sprung up about them. They discovered that many years ago, during Vietnam, Forge had called upon the mystical powers to avenge his fallen comrades in arms. But he did not understand the power he dealt with. The price demanded to enact such revenge was souls, and the spell took the souls of his fallen friends right from their bodies, without their permission. The spell complete, a gateway opened, letting the Adversary loose from his interdimensional prison, and freeing a host of demons as well.

Storm and Forge spent a year in that other world, while only moments passed on Earth. They discovered that this world had no soul, and that they were meant to provide it. Torn between letting the beautiful world die stillborn, and returning to fight the Adversary, the two somehow found their way into love again. With the technology gained from Forge's bionic leg and arm, he devised a way to return Storm's mutant powers to her, and return both of them home. Unfortunately, they returned to their world in the palace of the Adversary, high above the earth, as his prisoners. Also imprisoned there was the Goddess Roma, the protector of reality. The X-Men devised a way to reach the flying citadel, and managed to free Storm and Forge. Returning to the earth below, they finished the battle within the jungles of Vietnam.

They quickly discovered that they could not defeat the Adversary, nor return him to his interdimensional prison. It was Forge who knew the only way possible. It would take nine souls, the same number as his fallen comrades so many years ago, given freely to close the gate which admitted the Adversary to this world. The X-Men agreed, and so it was that Storm, Wolverine, Colossus, Dazzler, Rogue, Longshot, Psylocke, Havok and Madelyne Pryor gave their lives to save the world. Forge cast the spell which would seal the gate, but could not forgive himself the price which was so dearly paid. Neither did the millions of people watching the live broadcast on television. The X-Men, it seemed, were finally dead.

It was only moments after their death that the X-Men found themselves in the presence of the Goddess Roma again. She had brought them back to life for their courage and bravery, and offered them the chance to begin again. They accepted, deciding to tell none of their family or friends who had seen them die on TV, that they still lived. They had Roma transport them to Australia, where they began covert operations. Roma had also given them the ability to be invisible to any sort of audio/video device in order to keep up their charade of death, as well as entrusting them with a gem called the "Siege Perilous", a device which would allow them all to begin again, should anything go wrong.

For X-Factor, it began when they met head-on with a villain named Apocalypse. He launched his Four Horseman against X-Factor, introducing his newest addition, "Death", formerly Angel of the X-Factor team. When Angel had tried to commit suicide, Apocolypse had saved him, giving him new wings and changing his personality. In the end, Angel's loyalty to his teammates won out, and he turned against Apocalypse. Together, the team defeated him, even gaining the living ship which the villain had left behind.

The Fall of the Mutants had far reaching effects for both teams, as Angel tried to sort out his new persona, and the X-Men continued their charade of death. The Siege Perilous also caused some long reaching effects for the X-Men, but that is another tale.