Doctor Strange grapples with recurring nightmares about protecting a runaway teenager, America Chavez, who possesses the unique ability to traverse the multiverse. When America is attacked in New York City by a multi-dimensional demon, Strange and Wong rescue her. Realizing her pursuer is driven by powerful dark magic, Strange seeks help from Wanda Maximoff. However, he discovers that Wanda has been corrupted by the corrupting influence of the Darkhold. Consumed by grief over the loss of her illusory children, Billy and Tommy, Wanda desires America’s multiverse-jumping power so she can permanently relocate to a reality where her sons are real. When Strange refuses to surrender the terrified girl, Wanda launches a brutal assault on Kamar-Taj, slaughtering numerous sorcerers before America accidentally portals herself and Strange into a parallel reality known as Earth-838.On Earth-838, Strange is apprehended by the Illuminati, a clandestine council consisting of Mordo, Peggy Carter, Black Bolt, Reed Richards,
Captain Marvel, and Professor Charles Xavier. They judge Strange as a
dangerous threat due to his universe’s reckless use of the Darkhold. Before a verdict can be reached, Wanda possesses the body of her Earth-838 counterpart and infiltrates their high-security headquarters. In a horrific display of power, Wanda systematically massacres the Illuminati members one by one. During the chaos, Strange, America, and Earth-838's Christine Palmer escape into a desolate, decaying universe consumed by an incursion—the catastrophic collision of two realities.In this ruined dimension, Strange confronts a corrupted variant of himself who wields his own copy of the Darkhold. Defeating his dark variant, Strange uses the forbidden book to dream-walk, possessing the corpse of his Earth-838 counterpart to confront Wanda. Meanwhile, Wanda captures America and begins draining her powers to rip open a portal to her desired reality. Strange and Christine arrive just in time, but instead of fighting, Strange empowers America by telling her to embrace her own unique abilities rather than fearing them. America uses her newfound control to trap Wanda in a reality where she sees her beloved sons, who recoil from her in terror, realizing the monster she has become. Overwhelmed by remorse and heartbreak, Wanda uses her magic to collapse Mount Wundagore, seemingly destroying the Darkhold across all dimensions and sacrificing herself to seal the threat. America settles safely at Kamar-Taj to hone her incredible gift, while Strange returns to New York, bearing a physical third eye as the consequence of using dark magic, yet finally finding a measure of inner peace.