PlotEditIn Spanish class, Señor Chang informs the students of an upcoming academic event. He turns the floor over to Annie who announces that tonight at the library, she is throwing a Dios De Los Muertos party. Chang explains that students who attend get extra credit while he has to use his own free time to supervise the party without being paid. After he dismisses the class, Annie tries to get confirmation on who will be there. Shirley agrees, looking forward to her first college party. Britta scolds Jeff for not supporting Annie by attending the party. Pierce checks his cell phone to see if he sent the e-vite for the party and accidentally calls his mother. He tries to hang up but inadvertently switches to speaker and her incessant ramblings embarrass him in front of the study group.
Jeff flirts with the attractive professor. After she ends the class, he stays behind to flirt with her. Slater admits she is attracted to him and impressed by his boldness but states that as a rule she doesn't date students and leaves. Jeff follows passing Shirley and Britta in the hallway and they watch in disdain as he pursues the professor. Shirley is upset Jeff is going after another woman but Britta insists it doesn't bother her. Jeff continues to charm Slater but is unable to change her mind. Annie then shows up and presses Jeff for an answer about attending her party. As the coolest guy on campus, his attendance is necessary to ensure her party's success. Jeff tries to refuse but when she cries he finally agrees. During lunchtime, Pierce attempts to secretly take his pills, but Abed notices much to his embarrassment.
That night In the study room, Annie's party begins, and the study group members arrive in costume. Dressed in an unflattering squirrel costume, Britta laments about women who use Halloween as an excuse to dress sexy to Annie, who reveals a skin-tight skeleton outfit. Jeff shows up not wearing a costume while Pierce arrives dressed as the Beastmaster. He goes to the restroom to take his evening meds and runs into Star-Burns. He convinces Pierce to trade one of Pierce's pills for his own unaware that they are not recreational. Back at the party, Jeff sees Chang leave and follows him to the faculty Halloween party to see Slater. Britta and Shirley team up to bring him back angry that he bailed on Annie. When Annie calls for Jeff and the attendees realize he isn't there they begin to talk about leaving early.
Nearby, Pierce and Star-Burns begin to experience the effects of the pills they swapped. At the faculty party, Slater continues to resist Jeff's advances, worrying that word of a relationship would spread from his friends to the whole school. Jeff claims that he has no friends, but immediately they all start to appear. Britta confronts him about skipping out on Annie followed by Abed as Batman, who also condemns Jeff for his actions. Then Troy, dressed as Eddie Murphy, reports that Pierce is high and needs Jeff's help. It's then that Dean Pelton points out that Shirley is outside in the parking lot breaking the antenna off of Slater's car. Finally, Pierce arrives, high on Star-Burns' drugs, and makes a huge scene. Fed up with their interference, Jeff lashes out at each member of the group, driving them away.
Britta finds Shirley attempting to destroy Slater's office. Shirley admits that she is misplacing her anger and reveals that her husband returned for their wedding ring in order to give it to his new girlfriend. Shirley confesses that she pretended Britta was hurt in order to avoid her own pain. Britta realizes that she is also guilty of avoiding her own feelings regarding Jeff and Slater. As he returns to Annie's party, Pierce's drug trip progresses to hallucination, and Annie is unable to calm him. Back at the faculty party, Chang mocks Jeff's failure to score with Slater, and Jeff blames Greendale for draining his coolness. At Chang's suggestion, Jeff approaches Slater and straightforwardly pleads with her to have sex with him only to be shocked when she agrees.
They leave and walk past the library, where a crowd has gathered. Troy runs up and tells Jeff that Pierce is in the middle of a mental breakdown and only Jeff can help. Reluctantly, Jeff leaves Slater and approaches Pierce, who has barricaded himself inside a sizable fort made of tables and chairs. Pierce tells Jeff that the real reason for his freakout is having to face the fact that he is old. Jeff responds that Pierce has done a lot of living in just the last two months and should be proud. Reassured, Pierce pumps his fist which causes the fort to collapse. Abed swoops in at the last second and drags both men to safety. The episode closes with a dramatic Abed/Batman voiceover as the group recovers and continue the party together.
Eating candy after the party, Troy and Abed practice the Batman voice while musing about mundane thoughts.