Note: Although the New Mutants only briefly appeared in it, this follows events from Uncanny X-Men #202.
Sunspot's strength was being tested in the Danger Room. Magneto doubled the weight and Sharon Friedlander objected. When Sunspot struggled with the extra weight Tom Corsi tried to help, but Magneto commanded him to stay back. Sunspot's anger drove him to push himself further, and he ripped the weight apart. He stormed out of the Danger Room arguing that he only wanted to control his power so he could have a normal life. Magneto had succeeded in proving Sunspot was capable of more, but he was worried about whatever was eating away at Sunspot's soul.
In the boy's locker room, Sunspot had broken down into tears over a photograph of his murdered love, Juliana. He was distraught that the Beyonder could so easily have killed them if he had wanted to (see Uncanny X-Men #202).
In the New York public library, Shadowcat enjoyed reading stories of Norse Gods. Down on the subway, Magik was on her way to meet Shadowcat when there was a power cut. Everybody else ran at the appearance of the Beyonder. Magik attempted to attack him with her Soulsword, but was astounded when he grabbed the blade. As a being from Beyond, he was beyond rules that only allowed Shadowcat & Magik to wield the sword. He transformed Magik into Darkchild, but then expelled all of the dark magic out of her soul. He then left her inside the subway carriage, which flew out of the ground towards the school.
Back at the library, Shadowcat was growing tired waiting for Illyana to arrive when she was knocked out of her seat by the immediate arrival of the Soulsword. When she grabbed it, the Eldritch Armour covered her arm. Just as the librarian was about to through her out of the library for wearing outlandish clothes, they came under attack from a barrage of demons.
The other New Mutants were playing in the swimming pool. Karma rubbed sunscreen on Magma to stop her sunburn from getting worse, while Cypher & Mirage swam races. Suddenly they came under attack from a demon. Despite their best attacks, it was only stopped when Warlock absorbed the demon's lifeglow.
They were then surprised when the flying subway carriage landed on the lawn. Cannonball flew into the carriage where he spoke with Illyana. She spoke as if she was in a dream, and when she took his hand Cannonball also became dream-like. Speaking to the others they only wanted to spread the news of how the world would become a fantastic place when led by the Beyonder. The others were angry as they didn't want the Beyonder's will to be enforced upon them and lose free will as a result. Illyana tried to explain that she was so happy, having had the demonic side of her soul driven out of her. However, Cannonball grew frustrated so activated his power and grabbed Magma. He was stopped by Warlock, who in turn was stopped by Illyana. When she grabbed Warlock, he screamed that he could feel the alteration being enforced in his circuitry. However, the battle was soon brought to an end by the appearance of a gigantic shadowy demon.
Around the monster neck was a macabre necklace, from which hung Shadowcat's unconscious body. It revealed that Shadowcat had become the 'Guardian' in Magik's place, and while she had fought valiantly she did not have the necessary experience to wield the Soulsword. The demon then began an incantation to transform Shadowcat into a bloodstone inside the Beatrice Medallion.
The New Mutants fought the monster, but were unable to slow it down. Karma could not posses it's mind, while Magma couldn't burn it. Mirage implored Illyana to do something to help Shadowcat; her best friend. Since the Beyonder had driven the demon sorceress from her body, Illyana was unable to command the demon that was about to sacrifice Shadowcat. Tearful, she sacrificed her own soul be re-absorbing the Darkchild into her soul. She then commanded Cannonball to carry her up, in a similar attack to that on the Demon Bear (see New Mutants #20). She drove the demon back to Limbo by attacking it with the Soulsword, and reverted Shadowcat back to normal in the process.
Magik craddled Shadowcat's unconscious body on the lawn. When Shadowcat woke, she assured them that she knew they'd save the day.
Note: For the sake of understanding the character change, the name 'Illyana' temporarily replaces 'Magik'. This signifies the influence the Beyonder had over her, removing her status as the ruler of Limbo and therefore leaving her without any 'Magic' powers. The name 'Magik' is therefore used when the character re-absorbed the demonic influence in her soul.