While casting a magic spell, Anya and Willow accidentally summon Willow's evil double from an alternate universe.
Anyanka, the demon who used her power to grant wishes to let Cordelia unwillingly create a world without Buffy as Sunnydale slayer, failed since then to get top-rank demon D'Hoffryn to rehabilitate her, but finally gets a chance to succeed in her menial incarnation as Sunnydale High pupil Anya: Willow, who is frustrated as a girl and individual, always taken for granted, in Buffy's shadow and just got railroaded by principal Snyder to 'tutor', or in fact slavishly do the paper writing on her own, for a spoiled jock brat, hunky Percy West, who even explicitly barks at her as his menial flunky, naively accepts to help 'Anya' with a black magic spell. Willow realizes only too late she's really working for the wrong side, stops before Anyanka's power-amulet is revalidated, but still summons a parallel Willow from a black dimension where she's a master vampire, who now makes her grand entry in Drusilla-style at the Bronze, co-existing with gentle Willow. The gang has no time to mourn 'the best of us', who urgently must join in again with Angel, while the new official Watcher, Wesley Wyndam-Pryce from England, proves of little use, to survive and get rid of the dark 'alien' version, while both go undercover as the other...
- In a local crypt, Anya, who is now a mere human being, begs the demon D'Hoffryn, her former boss whom she has summoned, to create a temporal fold in time and allow her to go back and retrieve her amulet. The demon denies her request, and Anya vows to get the amulet back with or without his help. At school, Willow practices floating a pencil while Buffy does sit-ups in preparation for Slayer testing. When Buffy mentions Faith, Willow loses her emotional control and the pencil goes flying into a tree.
Principal Snyder tells Willow that she is going to be tutoring one of the basketball team stars, Percy West, in History. Later at the library, Giles asks Willow to re-attempt breaking into the Mayor's files. Faith and Wesley come in after training on the obstacle field; Wesley is a bit tired. Faith finds out about Willow searching through the Mayor's files and informs him of it. The Mayor presents Faith with a brand new, fully-furnished apartment and then tells her that he plans to have some vampires kill Willow and make it look like a random attack so she is out of the way and unable to access his computer.
Back at school, Oz meets up with Willow and informs her about a gig his band had the other night that she didn't know about. When Willow confronts Percy about tutoring him, he gives his own interpretation of events: that she is to do his work for him. Buffy and Xander pick the wrong moment to ask Willow if she recorded "Biography" for them the other night. Willow, offended at being labeled "Old Reliable," storms away, threatening to do something irresponsible change her look, cut class, or eat a snack between meals.
Anya finds Willow and asks her to help her with a spell, which she does. The spell involves chicken feet and the ritual pouring of sand over the representation of the object desired. The two perform the spell in an empty classroom, and as it's working, several scary images from "The Wish" flash before their eyes. Shocked, Willow moves, accidentally spilling some of the ritual sand on herself. With the spell over, and apparently unsuccessful, Willow is still very frightened by what she saw and refuses to try the spell again. In an abandoned warehouse, the same one from "The Wish", the vampire Willow from "The Wish" universe appears instead of the amulet.
Vampire Willow walks through Sunnydale and is very confused by this world where humans freely walk the streets at night. She enters the Bronze. Percy finds her and orders her to finish his paper; Evil Willow attacks him. Xander breaks up the fight and Evil Willow recognizes him from her world, only to be disappointed that he is "alive" (not a vampire). Buffy is surprised by Willow's new leather look, and even more surprised when Willow snarls at her with vampire face.
Later that night, Evil Willow is attacked by two of the Mayor's vampires who mistake her for the human Willow. She easily defeats them and "persuades" them to work for her. Buffy and Xander return to the library and tell Giles that Willow is dead. The three sit commiserating until the real Willow shows up. Xander tries to chase her away with a cross, and Willow merely looks puzzled; recognizing that this Willow at least is not a vampire, her friends simultaneously enfold her in a crushing embrace. Willow is dismayed to learn that there is a vampire walking around town looking exactly like her. When the gang turns to Giles for an explanation, his only response is "something strange is definitely going on." Xander in turn expresses his amazement that the Watcher Council let him go.
Meanwhile, back at the Bronze, Anya tries to get a beer at the bar, claiming she's 1120 years old, but settles for a Coke. Angel shows up looking for Buffy. Evil Willow and her new minions appear, taking control of the Bronze. Angel leaves to get Buffy and Oz watches as Evil Willow kills a girl. Anya, recognizing what has happened, approaches Evil Willow with the idea of restoring her to her own world (and Anya's amulet to herself).
Angel goes to the library and announces that Willow is dead, before noticing Live Willow standing there. They all head for the Bronze, but Willow turns back to get something and is caught by the Evil Willow. The two banter back and forth before finally Willow shoots her evil double with the dart gun (first seen in "Phases") and locks her up in the library cage. At Buffy's suggestion, Willow swaps clothes with her sleeping double. Uncomfortable in the leather attire (partly because it is tight enough to constrict her breathing), Willow does her best to pose as the Evil Willow while the rest of the Scooby Gang waits outside the Bronze.
Cordelia arrives at the library, dressed up to impress Wesley, and finds Evil Willow wearing Willow's fuzzy pink sweater locked in the cage. Before releasing Willow, Cordelia takes the opportunity to lecture her on the ethics of stealing boyfriends. Bored out of her mind, Evil Willow apologizes to get Cordelia to shut up, and Cordelia lets her out. Evil Willow shows her vampire face and pursues Cordelia, cornering her in a restroom. Wesley, hearing Cordelia scream, intervenes and forces Evil Willow to depart. Cordelia hugs him and asks what he's doing that night.
After Willow's not-so-convincing act at the Bronze, Anya points out to the other vampires that their leader is a fake. Willow screams a prearranged signal for Buffy, Angel and Giles to enter. As they fight the vampires, Willow retreats to the stage with Oz. Evil Willow then returns, throws Oz out of the way and starts choking Willow. Buffy breaks it up, but Willow shouts for her not to stake Evil Willow (just as Buffy had shouted, too late, to stop Faith from staking Allen Finch). Despite fully knowing what her evil doppelganger is and does, Willow cannot bear to have her staked. She convinces the others to send her back, arguing that Evil Willow should have the chance to survive in her own world, a suggestion which the homesick doppelganger accepts. With Anya's help they do so; Evil Willow is transported back to the middle of the brawl shown at the end of "The Wish". She has just enough time to smile at being returned to her reality before Oz grabs her and shoves her against a protruding piece of wood from the humans' cage. Evil Willow has just enough time to snarl "Oh fu**" before she turns to dust.
The next day, Buffy asks Willow if she'd like to go out that night, but she can't because of all the homework she has. Percy shows up, and before Willow can apologize for not doing his work, he presents her with papers on both Presidents Roosevelt- he wasn't sure which one the report was supposed to be on, and he didn't feel like risking Willow's wrath again. Because of this side effect of Percy's encounter with Willow's vampire double, her schedule is freed up.