Will explains that the glee club's next music lesson is to explore the easy listening/adult contemporary genre as an exercise in control and restraint. Kurt explains that this is not the easiest type of music for teens to relate to, and he reveals that there's a Facebook campaign demanding that the glee club perform a song by Britney Spears at the fall homecoming assembly.
Will refuses, thinking Spears is a bad role model, and glee clubber Brittany doesn't want to sing a Britney song either: her name is also Britney Spears, kinda: she's Brittany S. Pierce.
"I've lived my entire life in Britney Spears' shadow," she explains. "I will never be as talented or as famous." Brittany says she wants glee club to be a place where she can escape "the torment of Britney Spears."
Will closes the matter, but Emma suggests that the pop icon has come a long way and is the perfect symbol for the possibility of rebirth. Will, she says, is simply too uptight, while her dentist/new boyfriend Carl has helped her relax her control issues, inspiring her to even mix green and red grapes in the same bowl.
When Carl unexpectedly arrives at the school to take Emma to lunch (and further break her typical routines), he encounters Will in her office. Learning of Carl's interest in improving the oral hygiene of the high schoolers, Will invites him to speak to the glee club. Kids can't sing without teeth, right?
Karofsky and Azimio take Finn's varsity jacket away now that he's off the football team, ripping it in two. Finn takes a swing at them, but Artie intervenes, thanking Finn for his efforts to get him on the football team and subtly blocking the two players from escalating the fight as Coach Beiste quietly watches.
Carl teaches the glee club about oral hygiene by giving them a gum that turns the remaining plaque on their teeth blue. The bluest teeth are seen in the mouths of Rachel, Artie, and especially Brittany, who rinses her mouth with soda after eating and who has cavities in every tooth.
"Please don't pull out all my teeth," she begs Carl. "When I smile I'll look like an adult baby, but with boobs." Under anesthesia, Brittany fantasizes that she's a snake-charming Britney Spears singing "I'm a Slave 4 U."
Finn wonders how Rachel feels about his ejection from the football team. She's happy that she doesn't have to worry about what songs she might have to sing to him if he ends up in a coma, or about him running off with a Cheerio. Finn's annoyed by Rachel's blunt honestly about being pleased by his fall from grace, and he doesn't defend her when Santana criticizes her wardrobe.
Santana accompanies Brittany back to the dentist, and her perfect teeth make Carl reluctant to give her the nitrous oxide hit she wants. But Santana's "rockin' " health care plan persuades him to knock her out for a strong bleaching. Popping synchronized iPods in their ears, the girls imagine re-enacting Britney Spears and Madonna's "Me Against the Music" video, complete with a fantasy appearance by Britney Spears herself.
Filled with new confidence and believing that she's the most talented of the students - even more talented than Spears herself - Brittany demands every upcoming solo. Kurt argues that this is proof of the inspirational power of Spears, but Will's refusal holds firm. Upset, Kurt calls Will uptight and is sent to the principal's office.
During a check-up, Will and Carl engage in a "bro-to-bro" talk about their feelings for Emma. Carl asks Will to back off, and Will reluctantly agrees. To stop Will's teeth-grinding, Carl makes an unusual prescription: candy. He suggests that the reason Will and Emma didn't work out is because there's not an impulsive bone between the two of them. "You've gotta get ridiculous, bro," counsels Carl, urging Will to do things that feel good for no reason.
Rachel, also under Carl's sedation, fantasizes that she's the sexy singing schoolgirl in Spears' "... Baby One More Time" video (with the pop star herself as the schoolteacher), awakening with a nod to the "David After Dentist" viral video: "Is this real life?"
Rachel returns to McKinley sporting Spears' seductive schoolgirl look, flummoxing Finn when the male students salivate over her (including Jacob Ben Israel, who offers to give Finn his house and his parents for Rachel). She tells Finn that they can't control each other, and she gives him her blessing to try to become quarterback again.
When Will buys a flashy Corvette convertible to loosen up and impress Emma, he's confronted by his raging ex-wife, Terri, who insists that he can't keep his financial obligations to her if he buys a car he can't afford. But Terri decides that he should keep the car until he comes to his senses and returns to her, the only woman who can really love him.
Santana praises Rachel's new look, and Kurt again argues the importance of Britney Spears' inspiration. Will is interrupted by Sue, who discovered a salivating Jacob watching a video of the "new" Rachel. After exacting punishment on a naked Jacob, Sue demands that Will recognize the admittedly genius Spears as a dangerous "gateway drug" to sexual deviance among the students.
It's Artie's turn for a dental Spears fantasy, imagining her in a Cheerios uniform telling Tina how foolish she was for breaking up with him, then envisioning himself on the football field and pumping iron while singing "Stronger."
Coach Beiste overhears Artie asking Finn for further support in his bid to make the football team, and she decides to put them both on the team. Will also changes his tune, telling the glee club that they can perform a Britney song at homecoming - AND he'll be performing with them.
Rachel confesses to Finn that she's worried their relationship can only work if they're both losers, socially. Finn tries to reassure her, but she asks him to choose between her and football.
At the assembly, Will and the glee club perform a sexy rendition of "Toxic," whipping the student body into a chaotic frenzy and provoking Sue's wrath. She hits the fire alarm to end the assembly and is mowed down by the erotically charged students. Chewed out by a neck-braced Sue after the riot, Will confesses to Emma that his actions were prompted by his feeling that the boring person he'd been was not good enough for her.
Quinn makes a play to reunite with Finn, but he turns her down, saying that he'll always have feelings for her but is now committed to his relationship with Rachel. Rachel watches secretly, having put Quinn up to the proposition. In the music room, Rachel says that she's going back to the original "adult contemporary" assignment. She dedicates her song to Finn and admits that she was wrong to force him to make a choice. She sings Paramore's "The Only Exception" to show that she's realized she can't hold so tight to something she loves without risking ruining it, prompting Artie and especially Will to think long and hard about their own actions.