NOTE: This spoiler was submitted by Jeremy

The film opens in a space between universes, where a variant of Doctor Stephen Strange (Benedict Cumberbatch), “Defender Strange”, is running alongside teenager America Chavez (Xochitl Gomez). They are being chased by a demonic entity as they attempt to make their way toward the Book of Vishanti. As the demon attacks, Defender Strange attempts to hold it off but realizes that America’s powers may be what stops it, but since she doesn’t know how to control her powers, he attempts to siphon them out of her. The demon impales him and tries to kill America, but this triggers her powers and opens a star-shaped portal. Defender Strange makes one last move to attack the demon, pulling himself and America through the portal.

The main Strange wakes up from this, believing it to be a nightmare. He gets out of bed, gets dressed, and goes to a wedding. He is met by former colleague Nicodemus “Nic” West (Michael Stuhlbarg), who says he was also erased after The Snap. We then see that the wedding is for Strange’s former flame Christine Palmer (Rachel McAdams). After the ceremony, Strange talks to Christine, saying that he wished he could have made it work between them, but Christine assures him that it never would have ended well for them.

Outside, Strange sees a commotion as people are running through the streets. He puts on the Cloak of Levitation and takes to the streets, where he sees America being chased by a giant octopus monster, Gargantos. Wong (Benedict Wong) shows up to help fight the beast, ending with them ripping out its eye. America swipes Strange’s Sling Ring, but he and Wong catch up to her. He recognizes her from his dream, but she explains that he wasn’t dreaming, but rather seeing an alternate self.

The three go out for pizza, where America explains that she has the power to jump between any world in the multiverse, but she still doesn’t know how to do it on her own. She shows Strange and Wong the corpse of Defender Strange, which Wong recognizes as being marked by witchcraft. Strange then realizes who he has to go to.

Wanda Maximoff (Elizabeth Olsen) is with her sons, Billy (Julian Hilliard) and Tommy (Jett Klyne) (whom she created in “WandaVision”), living happily and peacefully at home. This is ultimately just one of many dreams that Wanda keeps having where she still sees them. Strange visits her in an orchard where she has retreated, asking her to help figure out what demons might be going after America. Wanda then tells Strange he can bring America to her, but he realizes that he didn’t tell Wanda the girl’s name. Wanda then goes into Scarlet Witch mode and undoes the hex that created the illusion of the orchard, showing the actual wasteland she has created. Wanda sent the demons after America because she wants to use her power to find a way back to Billy and Tommy, along with the help of the Darkhold (book of powerful dark magic) that she now possesses. She orders Strange to bring America to the Kamar-Taj by the next day, or Scarlet Witch will wreak havoc.

Strange and Wong keep America hidden at the Kamar-Taj while the other sorcerers get ready for an attack. A dark cloud appears over the temple, and Strange flies up to meet Wanda. Although he tries to reason with her, she has made up her mind, and she attempts to use her powers against Strange. The other sorcerers put their shields up, but Wanda eventually manages to get into the mind of one sorcerer, forcing him to run and causing the other sorcerers to drop the shields. Wanda proceeds to destroy the Kamar-Taj and kill several sorcerers. Strange and Wong run to protect America, with Strange trying to trap Wanda in the Mirror Dimension, only for her to manage to find a way out. After knocking out Wong, Wanda attempts to take America, but this triggers her portal powers, and Strange leaps forward to save America, although Wanda manages to hit the Cloak as they go through the portal.

After jumping through several trippy dimensions, Strange and America end up in Earth-838. Strange proposes they find the America of this universe to help figure out her powers, but she says that she has gone to enough dimensions to know that she is the only one of herself in the multiverse. They resolve to find the other Strange of this universe to help them find the Book of Vishanti, since it is the antithesis of the Darkhold and can be used to stop Wanda. On their way, America grabs pizza balls from a vendor, thinking they were free. The vendor (Bruce Campbell) chastises her, but Strange uses a spell to make the vendor punch himself repeatedly. They keep walking and pass through pads that project memories. Strange sees himself on a date with Christine where she gifted him the watch that he was wearing when he had his accident, and America sees herself as a child with her mothers. When she saw a bee, the fear triggered her portal powers for the first time, and she and her mothers were pulled from their universe, separating themselves ever since. America blames herself for what happened, but Strange tells her that she will find them again someday.

Strange and America find a statue dedicated to the Strange of that universe, only to discover that he died fighting Thanos. They then find the Sanctum Sanctorum, where the Sorcerer Supreme title belongs to Baron Karl Mordo (Chiwetel Ejiofor). He appears more friendly toward Strange than the one from his universe that wants to kill him, and he invites Strange and America inside. After they explain their situation to him, Mordo seemingly offers to help, but Strange and America soon realize that he drugged their tea, and he takes them prisoner.

Back at the Kamar-Taj, Wanda tries to use the Darkhold to dreamwalk, entering into the mind of her Earth-838 counterpart so that she can be with Billy and Tommy. One surviving sorcerer, Sarah (Sheila Atim), sneaks past Wanda and destroys the Darkhold, at the cost of her own life. Enraged, Wanda forces Wong to tell her what else he knows, or she will torture and kill the other surviving sorcerers. Wong relents and says that the Darkhold she had was a copy, and the original can be found at a temple in a mountain.

Strange wakes up in a cell, where he is surprised to find that this version of Christine is in charge of multiversal research. Mordo gets Strange and escorts him to meet The Illuminati, a team of heroes from alternate universes. They are made up of Peggy Carter/Captain Carter (Hayley Atwell), Black Bolt (Anson Mount), Maria Rambeau as Captain Marvel (Lashana Lynch), Reed Richards/Mr. Fantastic (John Krasinski), and their leader, Professor Charles Xavier (Patrick Stewart). Each of them believes that Strange cannot be trusted, as the Strange of that universe was not the hero that everyone in that world was led to believe. While 838-Strange did help defeat Thanos, he used the Darkhold and became corrupted, nearly creating an incursion that destroyed their world, so the Illuminati had him killed by having Black Bolt obliterate him. They do not trust Strange and see him as a greater threat than Wanda.

Wanda and Wong find the temple, where several of the guardians there recognize Wanda since her image is crafted into the walls. She finds the Darkhold and once again dreamwalks in her 838 self’s body. She infiltrates the Illuminati’s lair, killing off their robot guards. They go after Wanda but soon find themselves outmatched. Wanda removes Black Bolt’s mouth, causing whatever he says to implode his head. She then unravels Mr. Fantastic into nothing. Captain Carter puts up a fight, but Wanda hurls her own shield into her abdomen, killing her. Captain Marvel then tries to fight, but Wanda brings a statue down on top of her. Meanwhile, Strange eggs Mordo on in an attempt to get him to attack and free himself, which works and leaves Mordo stuck by himself.

Wanda finds America and Christine as the latter tries to get them out of there. Xavier goes into Wanda’s mind and attempts to pull 838-Wanda out from Scarlet Witch’s control, but she finds Charles and viciously snaps his neck. Strange gets America and Christine away, where they begin to run from Wanda. Christine brings them to a door that the 838-Strange knew how to open, and our Strange uses the broken watch as the key. They enter the dimension holding the Book of Vishanti, but Wanda catches up to them and destroys the book. She takes America and throws Strange and Christine into another universe.

Strange and Christine end up in a version of New York where reality has collapsed on itself. They find the Sanctum Sanctorum where another Strange variant, Sinister Strange, is alone, having corrupted this world using the Darkhold. Strange believes he can use that version of the Darkhold to stop Wanda, but Sinister Strange says he will only allow it if he can take Christine, as losing her was what drove him to corruption. Strange fights his evil variant using magic music notes, ending with Sinister Strange falling out the window where he is impaled.

Christine rejoins Strange as he decides the only way to get to Wanda is to dreamwalk himself. He goes into the mind of the Defender Strange corpse, turning him into a zombie. He opens a portal to the temple, only for damned souls to try and pull him down with them since dreamwalking is forbidden. Christine helps Strange fight them off, and Zombie Strange uses the souls to help pull him up to the temple. Wong fights off the guards before seeing Zombie Strange go in. Wanda uses her magic to decay the body further, but America soon manages to break free and hone her powers to fight Wanda.

America puts Wanda through the 838 universe where Billy and Tommy are terrified at the sight of their mother as Scarlet Witch. She attacks their actual mother before coming to realize that she truly has become a monster. As Wanda breaks down, her 838 self approaches her and reassures her that the boys will be loved and looked after. America pulls Wanda out and retreats with Wong. Wanda then tells Strange that nobody should ever use the Darkhold again, so she brings the temple down on herself to ensure that every version of the Darkhold will also be destroyed.

While waiting for America and Wong to show up, Strange tells Christine that he still loves her and feels that he loves her in every universe, but he has been too afraid to form a real relationship. They part on amicable terms just as America comes to bring them home.

The sorcerers rebuild the Kamar-Taj, with America now joining them in training. She tells Strange that she is glad that she fell into his universe, and he agrees with her.

Strange fixes up the watch that Christine gave him, seemingly ready to get his life back to normal. As he walks down the street, he becomes overwhelmed and falls to his knees, revealing a third eye has grown in his head like with Sinister Strange.

Mid-Credits Scene: Strange continues to walk down the street when he is found by a sorceress named Clea (Charlize Theron). She tells him that he has created an incursion because he used the Darkhold. She opens up the Dark Dimension and invites him to join, which he does.

Post-Credits Scene: The pizza ball vendor finally stops hitting himself and is relieved.

Brought to you by

Wanda Maximoff/Scarlet Witch has become corrupted due to her use of the Darkhold, a powerful book containing spells for dark magic. Hoping to be reunited with her sons Billy and Tommy, she attempts to kidnap teenager America Chavez, who possesses the ability to jump between any world in the multiverse. America teams up with Doctor Strange and Wong to stop Wanda, but after she destroys the Kamar-Taj and kills several sorcerers, she keeps Wong captive while Strange and America end up in another universe.

Strange and America are captured by the Earth-838 version of Baron Karl Mordo, who is part of The Illuminati, made up of heroes from other universes - Captain Carter, Black Bolt, Captain Marvel (Maria Rambeau instead of Carol Danvers), Reed Richards/Mr. Fantastic, and Professor Charles Xavier. They consider Strange to be the greater threat to the multiverse because the Strange of that universe was corrupted from using the Darkhold to defeat Thanos, leading to them having to kill him. Wanda uses the Darkhold to dreamwalk, or enter the mind of her 838 variant to be with her sons, but she slaughters the Illuminati (minus Mordo) and goes after Strange, America, and the 838 variant of Christine Palmer, Strange's ex-girlfriend. Strange attempts to get the Book of Vishanti, which can be used against the Darkhold's magic, but Wanda destroys it and captures America, sending Strange and Christine into another dimension.

After Strange fights an evil variant of his, he realizes he has to use the Darkhold to stop Wanda. He dreamwalks into the corpse of a dead variant of his, making his way to a temple where Wanda has taken America. Together, they fight Wanda, and America manages to hone her power and place Wanda in her variant's home, where Billy and Tommy see her Scarlet Witch form as monstrous. Wanda realizes how far she has gone and resolves to destroy every copy of the Darkhold, seemingly sacrificing herself and bringing the temple down.

Strange parts with 838-Christine and helps Wong rebuild the Kamar-Taj with other sorcerers, with America training under them. Strange then appears to be affected by the use of the Darkhold, as he grows a third eye like his Sinister Strange variant did. He is found by a sorceress named Clea, who tells him he created an incursion by using the Darkhold, and she invites him to join her in the Dark Dimension.