After a brief hiatus, the gleeks are back. Brittany has a new friend, an Irish exchange student she thinks is a leprechaun that only she can see. Quinn and Puck are kissing up to Rachel's mom Shelby in order to get their baby, Beth, back. They convince her she's run down and to let them babysit while she has some alone time. As part of her campaign, Sue is on a rampage to cut arts funding. Her "As Sue C's It" spot on the nightly news manages to enrage viewers into demanding Figgins cancel the school musical.
Mercedes is trying to convince Santana to come over to her all-female singing club, saying they'll get more solos, but Santana says she can't leave Brittany behind. At the next club meeting, the kids lament the loss of Mercedes and Finn stands up saying they need to move on and stick together. Blaine says they can find more talent, and Finn looks annoyed that Blaine is usurping his leadership role in the club. Schue tells the kids that he plans to sell ads in the program to raise the lost funding for the musical.
Finn encounters the Irish kid, Rory Flanagan, alone in a classroom. He's separating marshmallows from of a box of Lucky Charms for Brittany. He explains to Finn that Brittany promised him she'd let him into her pot of gold if he could procure an entire box of marshmallows for her. He admits he's lonely and Finn says they can be friends if Rory spies on Brittany for him and let him know if there are any rumors of more defections from New Directions.
Kurt walks into his dad's auto shop and asks him if he'll take out an ad in the musical program. When he finds out how the school cut the musical funding, he gets a group of local businessmen (all in the funeral business) to purchase the ad space in the program and save the musical. They all turn up at Figgins' office to let him know they disapprove of him cutting funding. Then Kurt's dad confronts Sue in the hallway and he tells her he plans on raising enough money to make sure she loses her race.
While babysitting, Quinn stashes questionable items around Shelby's house so that she can call child protective services and bust Shelby for being an unfit mother. Puck doesn't look totally supportive of her plot but doesn't try to stop her either.
After getting hazed by jocks in the halls of McKinley, Rory presents the box of marshmallow charms to Brittany. She's very grateful and tells him he's only two wishes away from getting in her pot of gold. Wish Number Two: Make Lord Tubbington poop candy bars. He asks her out to dinner, but she says she already has plans. He sings "It's Not Easy Being Green" while walking around the school alone.
Next we find out who Brittany has plans with. She and Santana dine at Bread Sticks. Santana asks her if they're dating, and Brittany asks her back if isn't having dinner a date, or how about the bath they took together last week? Santana is so happy she tears up. Brittany tells Santana she has a leprechaun. Santana asks Brittany to join Shelby's singing group. Brit says she needs to think it over. They hold hands at the table under a napkin.
Blaine sings a peppy song about last Friday night to get the gleeks into the spirit of things. Finn seems annoyed that Blaine is outdoing him in leadership and it looks like a rivalry is brewing between the two.
Santana confronts Rory in the hallway and intimidates him into trying to convince Brit to join Shelby's group. Back at home, Rory sneaks into Brit's room to put a couple of Baby Ruth bars into Lord Tubbington's kitty litter. Brit walks in and asks him what he's doing and he shows her the magic he created. Then he confides that Santana wished for her to leave New Directions, and Brittany agrees that she can't fight a wish made to a leprechaun.
Schue shows up at Bert Hummel's garage to tell him he should run for Congress against Sue. Bert is already one step ahead of him and has decided to start a write-in campaign. Schue agrees to help Kurt be his campaign manager.
Quinn tells Puck he needs to get a better job, because pool-cleaning--though it may afford him all the MILF nookie he can handle--isn't going to be enough to support Beth once they get her back. But then Shelby refers him to an indoor pool gig and Puck is appreciative that she thought of him, so he shows up at her place later that night to thank her again. Actually, he just wants to get inside so he can remove all the condemning evidence Quinn planted around the place. Beth cries the entire time until Puck plays a song on the guitar to calm her down. Is he singing Foreigner's "Waiting for a Girl Like You" to Beth or Shelby?
At school the next day, Rory tells Finn the news that Brittany is going to leave New Directions. Finn confronts Brittany and tries to convince her to stay, saying there is no such thing as leprechauns. Then he makes the irrevocable mistake of calling her an idiot for believing in such things. That crack seals the deal for Brittany, who walks away with Santana and into Shelby's rehearsal. The name themselves the Troubletones and put on a spirited 40s-style performance that makes Finn and Schue realize they're in trouble.
Finn tracks the girls down in the hall and congratulates them on a great performance. He wants them all to be friends no matter what and apologizes to Brittany. She accepts and then Rory steps in to say her third wish came true, her friends aren't mad she left the New Directions. But Brittany says she knows Finn is brokenhearted and realizes that leprechauns really don't exist. Santana pretty much tells him to disappear. Finn finds Rory about to get pummeled by a bunch of football players who want him to admit U2 is overrated. Realizing he should have stood up for Rory a while ago, he leads him into a rehearsal, where Rory wows everyone with his crystal-clear falsetto. While he sings, Puck is shown at making the moves on Shelby at her place.