The episode begins with Blaine giving Sam $50. Sam wonders what is going on. Blaine tells him that he knows that his family is struggling and that he wants to help. He tells Sam that he had seen him stealing pasta from the cafeteria. Sam takes him to a room and admits that he has been stealing pasta, but that was not for hunger; it was for art. He then shows Blaine his macaroni portraits and tells him that this is one of his guilty pleasures. Sam tells him that everyone likes something that he or she is ashamed of sharing with the world. Blaine tells him that he likes the band “Wham”.
Tina arrives and tells them that Glee club is cancelled for this week. Later, everyone gathers at the Glee club. Blaine tells them that Regionals is coming up and so they cannot miss a week’s practice just because they don’t have an advisor. They say that this week’s assignment is going to be ‘Guilty Pleasures’. Blaine explains that if they know each other’s musical guilty pleasures, they can become a more cohesive team for the Regionals. Sam and Blaine start with “Wake Me Up before you Go Go”. Next, Brittany tells Kitty that everyone in the school hates her and so she needs to do something to improve her negative image. She invites Kitty on Fondue for two.
During the interview she asks Kitty her guilty pleasure. Kitty tells her that it is too horrible to admit. She whispers it in Brittany’s ears. In NY, we hear Kurt’s voiceover telling us that his most secret guilty pleasure is the “boyfriend arm” that he sleeps with. He had ordered it online and no one knows about it. The arm makes him feel that he is sleeping with an arm around his shoulder. At McKinley High, Sam tells Blaine that he is a Barry Manilow fan and he is totally ashamed of it. Kitty and Brittany arrive at school and Tina, Unique and Marley demand to know what Kitty’s guilty pleasure is. Brittany blurts out “Spice girls”. The girls are excited and they decide that they should do one of their songs.
In NY, Santana has moved in back with Kurt and Rachael and she is still bickering about Brody. Kurt tells Santana that she cannot tell Rachael about Brody’s truth until after her big audition. Later, Santana suggests that they should play some prank on Kurt to take Brody off Rachael’s mind. They decide to put Kurt’s hand in water while he is asleep. They enter his room and are shocked to see the “boyfriend arm”. At the Glee club, Sam admits that he is a Manilow fan. He then sings “Copacabana”. Everyone joins in. After the song, they all admit that they love Barry Manilow and they thank Sam for making them admit it. Later, the girls discuss about which Spice Girl they want to be.
Tina arrives and she looks a little nervous and tells them she doesn’t know how to break the news to them. Moments later, Marley storms into the hallway and confronts Jake about singing a Chris Brown song. Jake tells the girls that he likes Chris Brown’s music and he feels guilty about it. He assures them that Chris is not his role model. He then cites some examples and tells them that they should be able to separate the art from the artist. In NY, Kurt gets Santana and Rachael their boyfriend arms. Rachael tells him that she is not lonely and that just because Brody moved out doesn’t mean that they wouldn’t get back. Santana finally tells Rachael that Brody is a gigolo and Kurt confirms it. Next, Blaine sings “Against All Odds”.
After the song, Tina asks him who he was thinking about and Blaine tells her that it was about Kurt. He then admits that it was also about the musical genius of Phil Colins and he is tired of making of fun of him. He declares that he is no longer in the closet about his love for Phil Colins. Next, the girls sing “If You Wanna be my Lover”. Artie notices Kitty during the performance. After the song, he mentions that he hasn’t seen Kitty look this happy to be a part of the team. Jake is up next and he sings “My Prerogative”.
Later, Jake apologizes for singing a Bobby Brown song. He says that he did not know that Bobby allegedly got Whitney Houston addicted to drugs. It was Artie who pointed this out to him after his performance. Jake then tells Marley that this whole week has made him crazy and he wants to things to be alright between them. In NY, Rachael arrives at NYADA to meet Brody. She confronts Brody about the gigolo thing. She is upset and she wants to know why he lied to her. She tells them that he had told her that if they could be honest with each other, things would work out well between them. Brody then asks her why she lied to him. Rachael is confused. He tells her that he knows that she slept with Finn when she had gone for Will’s wedding.
He tells her about Finn meeting him at the hotel room and punching him in his face. Rachel is surprised to learn that Finn came to NY to do this. Brody apologizes for what he does but he also tells her that he meant everything he said about her. Rachael admits that she wasn’t completely honest. She says that she used this whole thing partly to make Finn jealous and partly to fill her own personal heartache. They break up. Later, they sing “Creep”. At McKinley, Blaine is working on another Phil Colins song. Sam arrives in the auditorium and Blaine tells him that he wants to sing another song, before they are forced to put it back in the closet. Sam tells Blaine that he knows that his guilty pleasure is him. He knows that Blaine likes him and he does find it flattering. He assures Blaine that nothing will change between them and that he trusts him. They hug it out.
In NY, Kurt and Santana are bonding over a movie. Rachael arrives home and tells them that she and Brody broke up. She knows that they will be seeing each other at school and so they have decided to handle the whole thing in a matured way. She then thanks Santana and tells her that she is glad that Santana didn’t give up and made her see things. She also appreciates that Santana made Finn to come to NY and deal with Brody. Rachael promises that she will never doubt Santana’s “Mexican psychic third eye” ever again.
Kurt tells Rachael not to be sad. Rachael tells him that she is not sad. In fact, she is ready for her audition and also ready to date older guys. She also wants Santana to stay with them permanently. So, since she is the one who has had a heart break, she wants all of them to watch her guilty pleasure movie Mamma Mia. This leads to the three of them singing the title song ”Mamma Mia”. The episode ends.