The story's inciting incident is demonic invasion of New York City, and its main character arcs were the corruption of Madelyne Pryor into the Goblin Queen, and the final transformation of Illyana Rasputin into the Darkchylde.

Other non-X-Men books that tied into the storyline included the Spider-Man titles, which depicted the demonic transformation of the villain Jason Macendale (aka the Hobgoblin).

Illyana assumes that the entrapment spell was cast by S'ym, and so sees no reason to distrust N'astirh when he advises her that she can return to Earth by embracing her demonic power.

Meanwhile, N'astirh had made a bargain with Madelyne Pryor, agreeing to locate her son Nathan and manipulate the X-Men into killing the Marauders in exchange for her casting a spell that would make a permanent bridge between Earth and Limbo.

Driven to bloodthirstiness by N'astirh's Inferno spell, the X-Men attack the Marauders' headquarters, gleefully killing most of them in the ensuing battle.

With S'ym gaining the upper hand, N'astirh makes a desperate bid for victory by letting himself be infected with the Transmode Virus.

He then merges with Wiz Kid's spell-casting computer, exponentially increasing his magical powers and thus allowing him to bridge permanently between Limbo and Earth without Madelyne Pryor's help.

N'astirh is destroyed by the combined efforts of the X-Men and X-Factor, but Madelyne Pryor maintains the Inferno spell and threatens to kill her son Nathan as a demonic sacrifice to open the gate between Earth and Limbo.

She forcibly links herself to Jean Grey's mind and shows her Madelyne's entire life, including what she learned in Mister Sinister's laboratory.

Due to their mind link, part of Madelyne's personality was transferred to Jean, and she becomes determined to get revenge on Mister Sinister, now seeing him as responsible for all her sufferings.

When collected into a trade paperback, only the portions from The Uncanny X-Men, X-Factor, and The New Mutants were included, and the latter story line was presented separately from the first two.

Four years later (though due to a time dilation effect between Earth and Limbo, 26 years passed for them), Project Purgatory's surviving soldiers, led by General Ulysses, along with the new fully grown and powered surviving Inferno babies, both groups of which are battle scarred, and some of each having what appear to be grafted on demon body parts, have returned to Earth, apparently out to capture Illyana Rasputin.

[5] A spiritual successor to Inferno began in December 2022 entitled "Dark Web", which follows Spider-Man and the X-Men teaming up to fight Ben Reilly and Madelyne Pryor as they attempt to bring Limbo to New York.