Jacob Ben Israel ambush-interviews Puck on-camera in the hallways, asking about his reaction to Quinn and Finn pulling ten polling points ahead of Lauren and Puck in the race for McKinley's prom queen and king. After Puck explains their campaign strategy (intimidation and fear), Jacob throws in a hardball question emailed in by a viewer: "Where does Lauren keep your balls?" The notion that he's been neutered by his in-charge girlfriend throws Puck for a loop.
Principal Figgins announces that his planned junior prom entertainment, Air Supply, has canceled, and he wants to replace them with New Directions. Will resists - as does protesting prom coordinator Sue - arguing that the students have a lot of rehearsal and fundraising to do to prep for Nationals, but Figgins pledges Air Supply's pay ($400) to the glee club. Sue offers a list of the worst songs performed by New Directions, insisting that they be stricken from any performance list (Highlights: "Run, Joey, Run" and a mash-up of "Crazy in Love" and "Hair").
As Lauren bemoans her difficulty finding a prom dress, Mercedes feigns relief that no one's asked her. Will explains the performance situation, promising staggered onstage times so that the students can have time to dance with their dates. Upset, Mercedes storms out of the music room, and Rachel follows to check on her: Mercedes reveals that she's really disappointed that she doesn't have a date, and she really wanted the Cinderella experience for one night. The equally dateless Rachel suggests that they can go together, which Mercedes finds even more depressing, but Rachel insists that she has a plan.
Kurt asks Blaine to be his prom date, and - while he wants to go - Blaine explains his hesitation: at his previous school the then-just-out Blaine planned to attend a Sadie Hawkins Day dance with the only other gay boy enrolled, but on their way they were brutally beaten by three other students. Kurt gives Blaine an out but suggests that since Blaine couldn't face the bullies at his old school, they can face McKinley's together - and Blaine agrees.
Rachel and Mercedes make Sam an offer: they can all go together to prom. "Kind of a three-way date - but not the dirty kind," explains Rachel. Given Sam's family's precarious finances, Rachel and Mercedes offer up their prom budget and plan a no-frills experience, and Sam's onboard.
Looking to "goose up" their "pre-prom dress factor," Tina, Brittany, Santana, and Lauren invite Kurt to evaluate their gown selections ("like getting a thumbs-up from Joan and Melissa Rivers"). When Kurt reveals that he's going to prom with Blaine, Santana takes him aside, offering security services from her Bully Whips, a strategic sympathetic move that she freely admits thinks will bolster her votes for prom queen.
Puck approaches Artie, who's still mourning his breakup with Brittany, for help in being crowned "anti-prom king" by the school's shadowy community of troublemakers. Rather than win the real title, Puck hopes to reclaim his street cred as "a lovable but dangerous miscreant." He feels he HAS to spike Sue's punch, but as the prime suspect won't be allowed anywhere near it, and he wants Artie to do it while Puck creates a distraction. Artie admires the plan but worries it won't impress Brittany enough - he's desperate for a sure-fire way to earn her forgiveness and get her to accept his prom proposal.
Rachel asks the audio-visual club to evaluate her prom song selection, singing Adele's "Rolling in the Deep" - but the song is commandeered by the surprise arrival of old flame Jessie St. James, and the two join in an intense duet. Jessie apologizes for how he treated her, admitting that he traded love for a fourth consecutive National championship - "For a first, maybe; but for a fourth, no way" - and wants to make amends by taking her to prom.
Hearing that Jessie is joining Rachel, Mercedes, and Sam's prom-on-a-budget, Finn expresses his distrust of Jessie to Rachel. Rachel is upset by Finn's interference, and then softens, asking him to accept whomever she chooses the same way she's accepted Quinn and Finn, no matter how it hurts her. Finn confesses that he doesn't even want to go to prom, is tired of the campaigning Quinn's forced on him, and expects Quinn to hate whatever corsage he chooses for her. Still hurting, Rachel offers him advice on how to pick the flowers by matching them to Quinn's eyes.
Karofsky patrols the halls as a Bully Whip, and Santana escorts Kurt through the halls making a big show of protecting him from harassment.
Artie interrupts Brittany's home economics class and tries to apologize to Brittany with a song, in hopes of persuading her to be his prom date. Accompanied by the glee club guys, he sings Stevie Wonder's "Isn't She Lovely?" Brittany is moved, but she tells him that she's still going to prom on her own, working on herself and planning on dancing with other people's dates. She's still hurt by the fact that he called her stupid, and, though disappointed, Artie sincerely apologizes and leaves the class. Puck takes the opportunity to persuade Artie to spike the prom punch, and, with "nothing to live for," Artie agrees.
As Finn accepts Blaine's offer to jam with New Directions at prom, Burt informs the boys that his tux shop-owning buddy is giving them half off their formal wear. Kurt debuts his self-created kilted tux look, inspired by the recent Royal Wedding ("like gay 'Braveheart,' " admires Finn), but Burt isn't thrilled. He won't stop his son from wearing it, but he thinks it's a shameless bid for attention and will stir the pot. Blaine surprises Kurt by agreeing, thinking that they might not want to attract negative attention, but Kurt is determined to wear what he wants.
At school, Kurt tells Karofsky that maybe the reason no one's been harassing him all week isn't because of the Bully Whips' protection - it might be because no one cares that he's different anymore. Because now he can see past the bullying to understand Karofsky's pain, Kurt suggests that maybe Karofsky doesn't need to torture himself over his sexuality - maybe soon he can feel free to be himself. Breaking down, Karofsky apologizes, sincerely this time, for tormenting Kurt before, and Kurt believes him.
Quinn prepares for prom, envisioning her victory, and her beauty mesmerizes Finn - and she's pleased with the way the corsage he brought matches her eyes. As Rachel, Mercedes, Jessie, and Sam gather, Jessie tries to make Sam feel unashamed of his family's financial woes, unable to even get a job as a singing waiter himself. Hoping to launch a successful business, Jessie suggests opening a dance studio to help show choirs get an extra edge through footwork - a plan Rachel thinks is brilliant ("You'd be like the Show Choir Whisperer") and has her plotting to get Will to hire him.
Despite a prickly early exchange between Finn and Jessie, prom gets off to a rousing start: Sue zealously guards her grandmother's punch bowl as Puck, Sam, and Artie kick off the music with Rebecca Black's "Friday." Rachel takes the stage to perform Christina Perri's "Jar of Hearts," apparently directing the ode to promise-breaking not-so-subtly at Finn. Kurt admires the inclusiveness of this year's prom - Becky has a date - but is still concerned about the phoniness of the Santana/Karofsky coupling.
Despite a lack of music, Puck tries to distract Sue with some smooth dance moves, but she catches Artie in the act of spiking the punch. In her office, Sue pulls out a dental kit: pulling Artie's teeth "would get me sent to prison," but she intends to give him a cleaning that will result in intense oral pain OR he can rat out Puck for putting him up to it. Artie just wants to get back to the prom for one dance with Brittany, and for telling her the one thing he wants Sue declares him "the worst P.O.W. ever; John McCain is rolling over in his grave."
Blaine sings Black Kids' "I'm Not Gonna Teach Your Boyfriend How to Dance With You" onstage with Tina and Brittany, but during the dancing Finn tries to put a stop to Jessie's aggressive pawing of Rachel and their tension boil over into a fight.
Just as Artie's torture's about to begin, Sue's called away by Becky: "Code Blue in the gym, Coach!" Sue ejects Finn and Jessie, dashing Quinn's dream of prom royalty. The prom court candidates are assembled onstage, where Figgins reveals that Karofsky has been named king - but in a shocking twist, Kurt is named queen by write-in vote.
Kurt flees the gym in tears, pursued by Blaine: Kurt is devastated to learn that despite the daily bullying, no real progress has been made. Meanwhile in the ladies room, Quinn blames Finn's outburst on the fact he still has feelings for Rachel and lashes out, slapping Rachel (but is horrified at her own outburst).
Santana's also distraught that Karofsky won and she didn't; she just wanted to be accepted. Blaine offers to leave the prom with Kurt, but Kurt doesn't want to walk away. He decides to return and accept his coronation, showing the student body that he can't be brought down.
Quinn confesses to Rachel that she's afraid of losing everything, but Rachel tries to reassure her that she's more than just a beautiful girl.
Brittany explains that the students somehow recognize that Santana's not being herself, and if she'd just embrace her own awesomeness she'd have voted for her - like Brittany did - and she tells Santana to go back and be there for Kurt, because it will be harder on him than it is on her.
Sue resumes her interrogation of Artie, but he refuses to bend - and in the process reveals that he tried to spike the punch with lemonade, not gin, so Sue releases him ("You are seriously no fun to interrogate and almost torture"). Kurt takes the stage to be crowned by Figgins, offering a simple acceptance: "Eat your heart out, Kate Middleton." His bravery earns him enthusiastic applause from many of the students, but then he's called upon to share the traditional first dance with the prom king. As Mercedes and Santana begin to sing ABBA's "Dancing Queen," Kurt quietly urges Karofsky to come out and make a difference, but Karofsky can't do it - he bolts from the dance floor.
Blaine appears at Kurt's side and asks him to dance. As they spin around the dance floor, the glee club and the rest of the student body put their dramas and disappointments aside for the moment for one last dance at prom.