A limo pulls into the drive-thru at Sunnydale's Happy Burger restaurant. Inside the limo are not your ordinary customers, but rather vampires in search of the Slayer. One of them has cloven hooves in place of hands. On the way to their new hideout, one the vamps, Mr. Trick, picks up a diet soda... and the drive-thru employee himself. Later that night, Buffy dreams that she is dancing with Angel in the Bronze. During their dance, Buffy's claddagh ring slips off her finger and falls to the floor. Angel picks it up and clutches it in his hand, so tightly that blood starts to pour from his fist. As Buffy watches in horror, more blood seeps from Angel's chest in the exact same spot that she drive the sword through months ago.

The next morning, Principal Snyder finally re-admits Buffy into Sunnydale High, due to orders from the school board itself. Buffy needs to follow a few conditions, one of which being her ability to pass make-up exams for all the classes she missed last school year. A student again, Buffy visits the library with Willow, where they find a variety of spell ingredients on the counter. Giles tells Buffy that he needs to perform a binding spell on Acathla to make sure the demon remains dormant. In order for the spell to work, Giles needs to know the exact details of how Buffy defeated Acathla and Angel. Buffy lays out the basics, leaving out the part where Angel's soul was restored. Later that night at the Bronze, Buffy turns down a dance offer from Scott Hope, a fellow student who's had his eyes on Buffy for a while. Cordelia points out an interesting couple on the dance floor. As Buffy watches them dance, she begins to suspect that the guy may be a vampire on the prowl. As they head out of the Bronze, Buffy and her friends follow them out. Sure enough, the guy is a vampire. What does take the group by surprise is the girl's handling of the situation. Instead of screaming and trying to run for her life, the girl proceeds to beat the crap out of the vampire, stopping momentarily to greet Buffy by name and introduce herself as Faith. This new Slayer then takes the stake out of Buffy's hand and finishes off the vamp before heading back inside. While the group listens to Faith's wild stories, Cordelia finally puts the pieces together and realizes that Faith was called forth in response to Kendra's death. Faith is unlike Buffy, but she's different than Kendra also. Kendra was always uptight and on the defensive, while Faith is much looser and a little wild. During their conversation, Faith informs Buffy that her Watcher is currently at an annual retreat. Unaware of this Watchers' retreat, Buffy takes Faith to the library to meet Giles, who apparently has never been invited to any of the retreats. Buffy invites Faith to dinner at her place. While Buffy takes one of her make-up exams, Xander and Willow give Faith a tour of their school, pointing out all the hot spots where they brushed with death. Elsewhere, in an abandoned building, Mr. Trick explains to Kakistos how they could stay in Sunnydale and still operate around the globe, thanks to the internet. Kakistos has no interest in these matters. His only goal is to kill Faith, who caused the huge scar running over his right eye.

At the Summers home, Joyce is as impressed with Faith as the rest of Buffy's friends are, if not more so. Buffy excuses herself from the dining table to talk with her mom in the kitchen. Joyce suggests to Buffy that Faith could take over her duties as the Slayer, but Buffy reminds her that it's her job until she dies. Joyce is not happy to hear this, but she's slowly learning to accept it. After dinner, Buffy and Faith patrol for vampires. During their patrol, they get into an argument over Buffy's attitude towards Faith and the apparent fact that she's holding something in. Suddenly, several vampires attack the two Slayers. During the fight, Faith loses control on one vampire and repeatedly pummels it without even thinking of finishing the job with a stake. This leaves Buffy at the mercy of the other two vampires, who have her pinned to the ground. As one of them moves in for the kill, he mentions a name: Kakistos. Buffy succeeds in breaking their hold and killing one of them, while the other gets away. She then pulls Faith off of the brutally beaten vampire and dusts it with her stake. It seems Buffy isn't the only one with personal problems.

Buffy tells Giles about Faith's actions the next morning at school. She also tells Giles what the vampire said to her, and Giles immediately recognizes the name Kakistos. It's Greek for "the worst of the worst". Kakistos is a vampire who is so old that his hands have turned into cloven hooves. While Giles gets on the phone to contact Faith's Watcher at the retreat, Buffy runs into Scott in the hallway. He makes one last stab at trying to get Buffy out on a date. Charmed by his efforts, Buffy finally accepts. Scott then hands Buffy a box, saying it's a gift to represent their friendship. Buffy opens it and finds a claddagh ring inside, exactly like the one Angel gave to her that night on the docks. Overcome with emotion, Buffy drops the ring. As it hits the floor in the exact same fashion that it did in her dream, Buffy backs out of her date with Scott. Giles arrives and tries to help her, but Buffy insists she's okay. Giles then reveals that Faith's Watcher is not at the retreat -- Faith's Watcher is dead.

Buffy tracks down Faith to a sleazy motel. Buffy informs her that Kakistos is in town, which causes a look of fear and dread to wash over Faith's face. She immediately starts packing and starts to head out. Buffy stops her by mentioning her Watcher, who was killed by Kakistos. They hear a knock on the door, and Faith opens it. They are greeted by Kakistos, Mr. Trick, and a few of their cohort vampires. Buffy shuts the door and escapes out the back with Faith. The vampires chase them into a building. Seemingly safe for now, Faith explains that she witnessed Kakistos murdering her Watcher. Just then, Faith notices a couple of dead bodies on the floor. Buffy realizes that they didn't escape the vampires, but were instead driven into the building on purpose. As the vampires start to converge on them, Buffy and Faith run into the middle of the floor. Buffy takes on several vampires while Faith goes one-on-one with Kakistos. Paralyzed with fear, Faith can't fight back while Kakistos grabs her by the neck and repeatedly strikes her in the face. Buffy runs over to help, while Mr. Trick and a female vampire decide to abandon their master and head out into town on their own. Kakistos' body is so strong that Buffy's stake has no effect on him. Faith takes a cue from Kakistos' mockery and picks up a huge pointed beam. Before Kakistos can realize what she's doing, Faith drives it straight through his heart, causing Kakistos to crumble into dust.

The next day, the Watcher's council approves Giles' request to watch over both Buffy and Faith until a new Watcher can be assigned to her. Unable to keep her secret any longer, Buffy tells Giles and Willow the whole truth about what happened that night in the mansion. She explains that Willow's attempt at the restoration spell worked, and Angel was cured before Buffy drove the sword through him and sent him to Hell. After she heads out, Giles tells Willow that there never was a binding spell to perform on Acathla. He made the whole thing up so that Buffy would finally vent out whatever's been eating at her from the inside all this time. In the hallway, Buffy finds Scott and revives their plans for their weekend date.

Later that night, Buffy revisits the mansion where Angel, Spike, and Dru once stayed. Back at the scene where Buffy kissed Angel for the last time, she places the claddagh ring on the floor and bids her final farewell to Angel. After she leaves, the floor of the mansion begins to rumble. A bright light appears in the air, and the naked body of a man falls out from it and onto the floor. He lies there, afraid and shivering. It's Angel, who has returned from Hell... somehow.