Buffy is patrolling in a cemetery at night, but there is something wrong with her and with the demons she meets and kills: they are all singing and dancing. Buffy sings about her life after returning to Earth, and the way she feels detached from it ("Going Through the Motions").
The morning after, the friends find out such things have happened to them all. They suddenly burst into song again, first wondering what can possibly be the cause for this ("I've Got a Theory") - including a novel idea by Anya ("Bunnies") - and then, guided by Buffy, asserting their ability to deal with it together ("If We're Together"). They further learn that all the people in Sunnydale are forced to sing about their inner feelings ("The Mustard").
Later Xander and Anya sing together about things they would otherwise have never told themselves or each other, namely their fears about their coming marriage ("I'll Never Tell"), Tara sings a love song to Willow about the difference she's made in her life ("Under Your Spell") and Spike sings to Buffy about the torturous nature of their relationship ("Rest in Peace").
It seems that a new demon in town, Sweet, is responsible for all the singing. Unfortunately, some people are singing and dancing so much that they spontaneously combust, due to the dramatic release of their pent-up emotions.
Tara is chatting with Dawn, who says how happy she is that Tara and Willow made up. Tara doesn't remember a fight, but then touches the flower Willow gave her and realizes that something is off. She tells Dawn she has to go for just a bit and to stay in the house. Sweet has Dawn kidnapped by his minions, interrupting her as she begins singing a lament about her life ("Dawn's Lament").
Meanwhile in the Magic Box, Giles sings his thoughts, that his continued presence encourages Buffy to remain emotionally dependent on him and that he should no longer act as a father to her lest she never mature, thus he decides to leave again and return to England for good ("Standing").
Tara gets to the Magic Box and sneaks up to the stacks and finds out about a forgetting spell Willow had cast the evening before to make her forget about the fight, and decides to break up with her. Giles and Tara duet about leaving as they look at Buffy and Willow respectively, the two of whom are distractedly chatting ("Under Your Spell/Standing (Reprise)"). Meanwhile, Dawn is at home, singing about "Does anyone really care..." (Dawn's Lament) when she is grabbed by the giant puppet men and taken to Sweet.
When Dawn wakes up in The Bronze, she and two of Sweet's minions engage in an interpretive dance; this is Dawn's attempt to escape. ("Dawn's Ballet") Sweet explains that he thinks she is the one who summoned him, and intends to take her to the Underworld and make her his queen. Sweet and Dawn sing and dance, ("What You Feel") and when Dawn reveals that her sister is the Slayer, Sweet tells a minion to go and find Buffy and tell her "everything". He wants to see the Slayer burn.
Spike finds the minion outside the shop and hauls him in, where he tells Buffy where Dawn is and why, demanding that she come to the Bronze. Xander, Anya and Willow are eager to help save Dawn, but Giles insists that Buffy should go alone. Spike, dismissing Giles' stubbornness, offers to back Buffy up, but Buffy takes him to task regarding his wish for her to stay away from him, and a humiliated Spike skulks away, telling her he hopes she will dance until she burns, and her little sister too. Buffy leaves alone, once again singing about her inability to feel, as both a conflicted Spike and the Scoobies express their desire to fight along with her, accompanied by Sweet, who summons them in song ("Walk Through the Fire").
Arriving at The Bronze, Buffy starts to sing and dance defiantly, cynically expressing her current condition and the hardships of being the Slayer. The Scooby's show up (Spike as well, but he's going in through the alley) and in probably the funniest moment of the show, Giles says, "She needs back up! Anya, Tara!" and the two women run to Buffy and give her backup... vocals! As the song progresses she finally reveals to Sweet and her friends that, by resurrecting her, they had ripped her out of heaven rather than rescuing her from a hell dimension as they thought. As her friends react in horror to the admission, and once she has vocalized her anger and despair, she dances ecstatically to the point of showing signs of burning up, whirling and stomping like a wild woman. Spike arrives and grabs her arms, and very tenderly tells her that the only way to mend her wounds is to carry on living, "so one of us is living" ("Something to Sing About"). Dawn ends the song by saying "The hardest thing in this world is to live in it" This is the same line Buffy used when speaking to Dawn in Season 5 finale "The Gift"
Applauding, Sweet prepares to leave with Dawn, but it turns out that it is not Dawn who had summoned him, but Xander - who had not understood the implications - leading to the demon giving up on the queen matter and vanishing. As he leaves he points out that due to all the hidden feelings he caused them to reveal to each other none of them can claim "it ended well" daring them to say that they are really happy "once more with feeling" ("What You Feel (Reprise)"). The group does, questioning the pyrrhic victory they've achieved and what to do next ("Where Do We Go from Here?"). Spike stops in mid-refrain, disgusted with the situation and storms out. Buffy follows him into the alley, where Spike tells her to go back to her friends. She refuses and they sing one last reprise of their big numbers, as they move toward each other.
The episode ends with Spike and Buffy kissing, as the curtains fall, as predicted in the previous song's final verse, as the chorus swells one last time ("Coda").