On Ascension Day, Buffy and her friends prepare for the ultimate battle as they face off against the mayor and a horde of vampires.
Now mortally wounded Faith has thrown herself on a truck so Buffy can't bring her blood to Angel, she proves her love for him by insisting he drinks his medicine, slayer blood, from her neck, even if she has to beat him till his vampire instinct takes over long enough. He does pull away before she's drained and carries her, unconscious, to hospital for a human blood transfusion. The mayor brought Faith in at the same ward; already healed Angel stops his attempt to smother Buffy, who soon feels 'ready for war' herself. Both camps make attack plans. Wesley has returned to help fight the ascension against the council's will, asks Cordelia to follow him to England in case they prevail, sealed with kissing but the chemistry doesn't kick in; Willow and Seth are accomplished, matched kissers, Angel confirms his intention to leave after a victory stands. The next morning is the graduation ceremony, with the mayor's guest speech about graduating as ascension, till a solar eclipse starts his transformation into a dragon-size demon in basilisk-shape; his vampire goons attack, faced by Angel, Wesley and other men for the possibly final fight. The gang made sure their whole graduating class came with hand-arms hidden under their gowns, under 'military veteran' Xander's field command, with Giles manning the secret weapon...
- After stabbing Faith, Buffy stands stunned for a few minutes, then drops the knife and escapes from the rooftop just before the Mayor enters Faith's empty apartment with a group of vampires. The Mayor, devastated by the thought of losing Faith, orders the vamps to find her.
At the library that night, Xander and Giles search for information on the demon Olvikan, while at the mansion, Willow watches over Angel; delirious, he mistakes her for Buffy and confesses how much he needs her. When Buffy finally returns, she sends Willow away, and tells Angel that the only cure for the poison is Slayer's blood. Angel asks about Faith, but Buffy tells him that she killed Faith. However Buffy knows another source of the blood...herself. She suggests that if he's careful he can drink enough to cure himself without killing her. He refuses, weakly, but she won't take no for an answer and strikes him to bring out his vampiric nature. Eventually Angel vamps out, and Buffy exposes her neck to him. Angel can resist no longer and bites her. He drinks deeply, however he loses himself in the pleasure of drinking human blood. Seeing that Angel isn't going to stop feeding and quickly approaching the point of no return, she tries to get him off to no avail. Angel finally lets go, cured of the poison but Buffy slips into unconsciousness, suffering major blood loss. Angel rushes Buffy to hospital, explaining that she's lost a lot of blood. In another room, a doctor tells the Mayor that Faith's head trauma coupled with massive blood loss means she is unlikely to regain consciousness. The Mayor notices Buffy in bed, and, enraged by her attack on Faith, tries to smother her until Angel tears him away. The Mayor leaves with a message not to miss the second act of the show. Meanwhile the rest of the Scoobies arrive at the hospital and when Oz notices that Angel is cured, Angel explains that Buffy put Faith in a coma and that she made him drink from her. Xander takes him to task about this but Giles takes charge and orders Angel to return to the mansion.
Dreaming, Buffy visits Faith, who is packing up her apartment. Faith says human weakness never fades, "Not even his." Faith tells Buffy that it's time to go and then Buffy wakes up in the hospital bed. She walks over to Faith and kisses her forehead, then strides into the waiting room, telling her friends to get ready for war.
At school, Buffy outlines a plan which relies heavily upon Xander's mystical military training and exploits the Mayor's human weakness - Faith. Meanwhile, the Mayor explains to his group of vampires that when the eclipse takes place, he wants the vampires to keep the people from running, as he must feed within the first few minutes to sustain the change. Angel and Xander get to work creating a bomb, which Giles is assigned to detonate. While putting away books, Cordelia and Wesley finally kiss, and discover they have no sexual chemistry. Oz reassures Willow that "We'll make it through this", and they kiss, passionately. In the library, Angel tells Buffy he'll simply disappear when the battle is over, because to say goodbye would be too painful. Buffy is left alone, with the most vital weapon to be used against the Mayor... Faith's knife still stained with her blood.
At graduation, the Mayor starts his speech, but is interrupted by the eclipse, which triggers his transformation into the 60-foot snake demon Olvikan. The parents scatter, and the students gather together in one large group. At Buffy's call, everyone rips off their robes, revealing weapons and crosses. Under Xander's guidance, the students attack the demon with flame throwers and flaming arrows. Principal Snyder is eaten by the snake-demon in mid-lecture. Some students break from the group and run in fear - right into the mayor's vampires approaching from behind. Students in the rear mount a ranged counterattack and drive the vampires back into a group of students at the rear led by Angel and Wesley. A melee ensues as both groups attack the vampires (although Wesley goes down in one punch after two seconds). Cordelia stakes her first vampire, but other students - including Larry and Harmony - are killed. Suddenly Buffy shouts at the Mayor, brandishing Faith's knife. Buffy boasts about stabbing Faith, and then calls him a dick (a play on words, since the Mayor's name is Richard, which is commonly shortened to "Dick"). She then runs into the school and the Mayor, enraged, chases her. Buffy runs for her very life as the Mayor smashes through the hallways. After leading the Mayor into the library, Buffy escapes the building through a window. The snake smashes through the doors to find the room laced with explosives, and speaks his last words: "Well, gosh." Giles hits the plunger, exploding the Mayor as well as Sunnydale High.
As Wesley is taken away in an ambulance, Giles congratulates Buffy on a job well done, presenting her diploma which he pulled from the rubble. After he leaves, Buffy sees Angel at a distance. The two stand there, near tears, until Angel turns and walks away. Buffy meets up with her friends and they prepare to head for home, but Oz says they should take a moment to reflect... they survived. Buffy remarks it was a hell of a battle. "Not the battle," Oz clarifies, "high school." After a few seconds of reflecting, the gang decide to head for home. As the friends walk off into the distance, we see a charred Sunnydale High Yearbook nearby, stating "The Future is Ours!".