Brittany chats with foreign exchange student Rory Flanagan (Damian McGinty, winner of "The Glee Project"), whom - thanks to his Irish brogue and green wardrobe - she's mistaken for a magical leprechaun. When she makes her first wish (for a box of Lucky Charms cereal made with all marshmallows), Rory plays along, and her delusion continues.
On the down low, Quinn and Puck give Shelby a gift of concealer, commenting that she's looking a little tired with all of her new commitments (though Puck says she still the "most tappable" teacher at McKinley). The two offer to babysit their daughter, Beth, for Shelby whenever she needs a break.
Congressional candidate Sue aims her anti-school arts platform right at the glee club's planned production of "West Side Story," criticizing the musical's budget on "Sue's Corner" and encouraging people to call McKinley to complain. As a result, Figgins is ready to cave to the pressure Sue's orchestrated. Will, after initially protesting, offers to raise the money for the production himself.
Mercedes appeals to Santana to abandon New Directions and join Shelby's second glee club (assembled initially as a vehicle for talent-impaired Sugar Motta). Mercedes promises that she and Santana will get all the solos and duets, and that the female-centric nature of the group should appeal to Santana. But Santana feels that she shouldn't leave Brittany alone in New Directions, and a shocked Finn overhears Mercedes suggesting that Santana bring Brittany to the new glee club as well.
Tina is emotional over Mercedes' departure, and Puck thinks that her loss is a crippling blow for the club's chances at regionals. As a result, Will finds himself facing an overwhelming tide of negativity among the students: Quinn blames him for being too hard on Mercedes at Booty Camp, Tina blames Artie for not giving Mercedes the Maria role, and Kurt is still fuming that Rachel's running against him for class president.
Finn tries to prevent them from turning on each other, but when Blaine takes his side, Finn lashes out at him, suggesting that he's a spotlight hog. Will tries to calm the discord by unveiling his plan to raise funds by selling ads in the musical's program, and Kurt volunteers to spearhead the effort.
After testing Santana's loyalty to New Directions, Finn meets Rory and is surprised to learn that Rory's something of a Finn Hudson fan. Rory, who loves everything about America ("especially NASCAR, your half-black President, and Victoria's Secret catalogs"), is staying with Brittany's family and - aware that she believes he's a leprechaun - is creating a fully marshmallow box of Lucky Charms for her. Still a virgin, he believes that if he grants her three wishes he can "get into her pot o' gold." He asks Finn to be his friend, and Finn agrees on the condition that Rory keeps him apprised of potential defections from New Directions by Brittany and Santana.
Shelby leaves Beth in the care of Quinn and Finn (Beth still cries whenever Quinn holds her), but rather than spend the time bonding with their daughter, Quinn has a secret agenda: she wants to plant evidence that suggests Shelby is an unfit mother. The "evidence" includes books on baby sacrifices - Quinn says that Shelby's so sleep-deprived she'll never notice. Puck is reluctant to frame Shelby, but Quinn persuades him that they'll get Beth back if her plan works.
Kurt tries to sell his dad, Burt, on placing an ad in the musical program. Burt is incensed to learn that the show won't go on without funding, yet Sue's cheerleading program's exorbitant budget remains intact. He recruits a trio of funeral home operators from his Rotary Club to fully fund the musical, and he confronts Sue about her schemes, promising to also raise money to oppose her campaign. Sue fires back with a volley of threats and insults, but Burt isn't scared off, telling Will "I'd love to see that woman lose, just once."
Rory delivers Brittany's first wish, and though he's one step closer to her pot o' gold, he's constantly being knocked around by the school's bullies. He walks the halls wistfully reflecting on Kermit the Frog's "It's Not Easy Being Green."
Meanwhile, Santana asks Brittany if they are actually dating, and Brittany reassures her - and she promises that if it causes any controversy to her class president campaign, she'll use one of her leprechaun wishes to win the election. Asked about her own wishes, Santana admits that she's thinking about joining Shelby's show choir, and Brittany asks for a day to consider if she, too, might leave New Directions. Then Brittany grants Santana's other wish and holds her hand.
Puck's so wrapped up in his thoughts of Beth that he doesn't realize he's alienating the prowling cougars he services with his pool cleaning business, and Quinn's on his case to find a more lucrative job so they can support Beth. Quinn's façade begins to crack, as she reveals that with everyone else making their plans for the future, she views Beth as her last remaining chance to have something perfect for herself that even she can't screw up. Then Shelby passes on a contact to Puck that could land him a year-round job cleaning her condo's pool.
With Will's announcement that the musical's back on, Blaine offers the glee club a choir room performance just to remind them what glee club's all about: he sings a free-spirited rendition of Katy Perry's "Last Friday Night."
Santana, however, believes that the musical will shut out everyone but Rachel and Blaine. She then confronts Rory, revealing that she knows he's playing along with Brittany's delusion and that she'll reveal him - unless he grants her a wish. Rory makes Brittany's second wish come true (she believes he's turned her cat Lord Tubbington's poop into candy), and then he tells her about Santana's single wish: she wants Brittany to come with her to the new glee club. Brittany can't deny Santana her one magic wish, so she decides to leave New Directions.
Will visits Burt at the auto shop, attempting to persuade him to run against Sue. Burt's one step ahead: he's already had his wife, Carol, check out the rules, and he plans to run as a write-in candidate. Because he feels that glee club saved Kurt's life, Burt is determined to keep arts programs alive - and Will agrees to help Kurt manage his campaign.
Puck drops by Shelby's condo to thank her for the successful referral, telling her it means a lot to him because not many people believe in him. While Shelby tries to soothe a crying Beth, Puck discreetly sweeps the place clean all of Quinn's planted telltale signs of abuse, then he calms Beth's crying by singing a gentle version of Foreigner's power ballad "Waiting for a Girl Like You."
Shelby admits that while she's wanted to be a mom, she's felt overburdened doing it on her own - and worse, she misses sharing the best moments with someone who loves Beth as much as she does. Puck promises to be there for Shelby whenever she needs him.
Rory delivers his "top secret intel" to Finn, who tries to persuade Brittany to stay even as Santana argues for her to join her defection. In the heat of the argument, Finn reveals that Rory's not really a leprechaun and that Brittany needs to "grow up and stop being such an idiot." He apologizes, but she tells him that all the glee club boys call her that and as their leader he's the worst of them. It's mean, it's bullying, and she won't take it. She and Santana then tell Mercedes that they're throwing in with her all-girl show choir.
Local TV news anchor Rod Remington informs Sue that campaign law requires that the station provide her opponent with equal time. Burt appears on the air to rebut Sue's arguments, exposing how inflated her Cheerios budget is and urging voters to stand behind much-needed school arts programs by writing in his name on election day.
When Brittany and Santana show up for their new glee club, Sugar Motta welcomes them as "more backup for me," but Santana immediately puts her foot down: she doesn't intend to trade one diva-driven show choir for another. She tells Sugar that if she turns down the attitude she can be on a winning team for once. As the newly formed Trouble Tones, the girls perform a retro-'40s version of Christina Aguilera's "Candyman." Observers Will and Finn agree: this means big trouble.
Finn approaches Mercedes, Santana, and Brittany in the hall to sincerely wish them well and to deliver a more heartfelt apology to Brittany, who accepts it.
Rory tries to use the unfolding events to his advantage, telling Brittany that he's granted her third wish: she wanted to leave glee club without hurting anyone's feelings, and Finn was happy and smiling - so now Rory wants to collect his reward. Brittany informs him that Finn was only smiling to cover his heartbreak, and that she now realizes that leprechauns aren't real - and she turns her back on them. Santana adds in a final wish: she wants Rory to do the school a favor and simply disappear.
At Breadstix, Burt and Carol discuss what Burt's campaign will mean with Kurt and Finn: Finn seems concerned about what's ahead, and sensing his lack of a future plan Burt suggests that he may now need help at the auto shop; Kurt is concerned about what the campaign - and especially Sue's dirty tricks - might do to Burt's health, given his recent heart scare. Sue then shows up to deliver a heart-stopping hamburger to welcome Burt to the campaign. She warns him that she's become refocused on her original goals: in memory of her sister, she wants broadcast the lack of special education programs, and she'll be aiming to shift the budget away from the arts to support them.
Finn saves Rory from yet another round of bullying, and he offers to grant Rory a wish of his own: friendship. He brings Rory to New Directions, telling the glee club that there's always new talent waiting to be discovered. A regular singer at Sunday mass, Rory auditions with Teddy Thompson's "Take Care of Yourself," and students agree with Rachel's assessment: "He's magical." Meanwhile, as Puck helps Shelby in taking care of Beth, they share their own magical moment with an unexpected kiss.