Graduation Day has finally arrived, and everybody has a different perspective on it. Cordelia's concerned about the color of their graduation gowns, Buffy doesn't quite get the whole graduation deal, and Xander, who woke up with a bad feeling in his gut, fears he won't survive Graduation Day. He's found out that Mayor Wilkins will be their commencement speaker.
Faith isn't concerned about graduation, but she does have an interest in college. She pays a visit to Professor Worth, a professor at the college. The Mayor wants him dead, and Faith handles the job.
While enduring his final classes, Xander mentions the Ascension to classmate Anya, and her ears perk up. She knows about it, and Xander brings her to the library, where Buffy, Giles and Wesley are trying to figure out why the Mayor killed Professor Worth. Xander announces to them that Anya not only knows something about the Ascension Ð she's the only living person who's been to one.
She tells them that about 800 years ago, in the Koskov Valleys above the Urals, there was a sorcerer there who achieved Ascension. He became the embodiment of the demon Lohesh, and she was there to witness it. Lohesh, a four-winged soul killer, decimated the village within hours Ð only a small handful of people survived. Anya explains that an Ascension means that a human being becomes pure demon. She tells them that all the demons that walk the earth are tainted, or human hybrids like vampires, but that a pure demon is different. She doesn't think this sounds like Lohesh, though, because the rituals are all different. Just as she says this, the Mayor bursts into the library.
The Mayor begins to talk about how powerful he'll be once the Ascension happens. Buffy makes a remark, and the Mayor responds by saying when the Ascension comes, he'll eat her. Giles, incensed by this, stabs the Mayor with his fencing foil. Of course, this doesn't affect the Mayor, who merely pulls the blade from his chest and walks away, grinning about his commencement address.
With the graduation ceremonies fast approaching, everyone's getting nervous. Anya, who has seen what an Ascension is like, plans to skip town, though Xander tries to get her to stay and help. She proposes to him that he could leave with her, and tries to persuade him to come, but he's committed to staying to help his friends, and declines. Buffy is also anxious, and tries to convince her mom to leave town, saying she won't be able to concentrate on stopping the Mayor if she has to worry about her mom. She doesn't want to leave, but Buffy finally convinces her. Willow, who is researching in the hopes of finding a spell to stop the Ascension, is nervous, too. To help her relax some, Oz plants a passionate kiss on her. Soon they are making love. As they lie together afterwards, they both agree that everything feels different now.
At Professor Worth's apartment, Buffy is investigating, trying to find some information that may be helpful, and Angel comes to help her out. They gather a box of documents, and prepare to take it to Giles. Outside the professor's apartment, Buffy and Angel talk about their relationship, and Buffy expresses her frustration. Suddenly an arrow pierces Angel through the back. We see that Faith has shot the arrow. When Buffy tries to help Angel up, he collapses; he's sweating, burning up. The arrow is poisoned, he tells her. In a panic, Buffy rushes Angel back to the library.
At the library, Giles and Wesley are discussing why the professor's research was of interest to the Mayor. He was doing research in old lava beds near a dormant volcano, and he found a large carcass buried underneath by an eruption. In his paper, Professor Worth suggests that the carcass may be some heretofore-undiscovered dinosaur. Giles thinks that perhaps it could also be a demon, which would explain why the Mayor would want to keep this kind of information secret Ð if the carcass was a demon, then it means that the demon can be killed, which would mean that the mayor is only impervious to harm until the Ascension. Once he's in demon form, he could be killed.
Buffy brings Angel back to the library for help tended. Willow is summoned to figure out what was on the arrow Faith shot Angel with. Wesley contacts the Council to see if they can help, but he returns to tell Buffy that they said they wouldn't help Ð it's not Council policy to cure vampires. Buffy is defiant, but Wesley explains that they're talking about laws that are older than civilization. Buffy says she doesn't care how old the laws are Ð she's talking about watching her lover die. The Council's orders, Wesley reminds her, are to concentrate on the Ascension. Buffy says she doesn't think she's going to be taking any more orders, from Wesley or the Council, and tells Wesley that she's not working for them anymore. Wesley pleads with her, arguing that Faith poisoned Angel to distract Buffy, and now the strategy is working. Buffy replies that she has a strategy of her own, and Wesley is not in it. This is mutiny, Wesley cries. Buffy says she likes to think of it as her graduation.
Willow, meanwhile, has figured out what the poison is Ð its Latin name translates to "killer of the dead." Oz finds that the only cure for it is to drain the blood of a slayer. Buffy has an idea Ð she'll get Faith's blood, and she'll kill her first if she has to. No more playing around, she says Ð she's ready to take on Faith to the death. Opening the closet in the library, she removes a dagger Ð the one the Mayor gave Faith, the one Faith used to kill one of the creatures from the Box of Gavroc in the cafeteria when the box was exchanged for Willow Ð and takes it with her. Oz and Willow figure out where Faith's apartment is, and Buffy heads there for the confrontation.
The Mayor, meanwhile, is busy preparing for the Ascension by performing the Ritual of Gavroc. Sitting at his desk in his office, he gleefully devours the creatures from the Box of Gavroc, feeling stronger with each one he eats.
Buffy arrives at Faith's apartment, and the battle soon begins. The furious fight leads them crashing through the window of Faith's apartment and onto a lower roof below. When they land, Buffy slaps handcuffs onto Faith's wrist Ð and the other cuff is already attached to her own wrist. The fight continues between the two handcuffed slayers until Faith breaks the cuffs apart. Buffy staggers back, and pulls out Faith's dagger. They tangle some more, and the fight moves toward the edge of the roof. As they peer over the ledge, Buffy stabs Faith. Faith, stumbling, steps on to the ledge, leans back and says goodbye, falling back into a passing truck. Buffy rushes to the ledge, but she's too late. The truck, with Faith, and her slayer's blood which Buffy needs to save Angel, is driving away.