Arriving on campus to find Britta & Annie busy with a Gulf oil spill fund-raising drive, a horrified Troy announces that he stumbled upon the dead body of Pierce’s mom in their garage. Though his friends are quick to express their sympathy, Pierce claims that, according to his Buddhist faith, his mom is simply being vaporized in advance of her eventual reincarnation. When the study group arrives for their Anthropology class while discussing the death, they discover that, with Professor Bauer’s suspension, the class is now being taught by the school’s psychology teacher & Chang’s nemesis, Professor Duncan. As Duncan looks to enforce a restraining order against Chang that he obtained following a violent confrontation the year before, Jeff is stunned when his physical exam reveals he has high cholesterol. & while Jeff struggles with the consequences of aging, Britta accuses Annie of playing the sexy schoolgirl to get the men on campus to donate to their cause. ...

Between dressing up as Lady Gaga, saving money on catering by using surplus military rations, & crafting a playlist that relies heavily on the Ghostbusters soundtrack, Dean Pelton is certain that he’s put together Greendale’s best Halloween costume party ever. Yet things begin to unravel when Pierce falls ill after feasting on the party’s tacos. Though Rich, a part-time pottery student & classmate of Annie’s who is also a doctor, suspects food poisoning, he’s cautioned by Dean Pelton not to cause a panic. But when a zombie-like Pierce starts biting his classmates on the neck & turning them into zombies, too, the dean & Rich realize they have a bigger problem on their hands. ...

When the girls arrange to take a women’s studies class together, the last thing they want is for Abed to enroll, too. When he does, their first instinct is to do whatever it takes to make sure they don’t have to sit with him in class. However, after he proves exceptionally adept at putting down the class’s trio of mean girl queen bees – Meghan, Jen & Tracy – they see that having Abed as a sidekick has its benefits. Meanwhile, as the guys try to avoid including Abed in their basketball game, Jeff & Troy stumble onto a secret garden paradise being maintained by Greendale’s groundskeeper, Joshua. ...

As the study group is preparing dioramas for the Environmental Club’s Green Week, Dean Pelton questions Jeff about his alleged enrollment in a class called Conspiracy Theories in U.S. History. Though Pelton suspects he’s running a scam to get unearned course credit, Jeff insists the class is real & offers to introduce him to its instructor, “ Professor Professorson.” Yet, as Jeff recklessly presses ahead in the hope that Pelton will give up before his ruse is exposed, he’s stunned when someone steps forward claiming to be Professorson. Meanwhile, with Pierce & Shirley off on a road trip to find the best hamburger in the country, Troy looks to avoid spending the night alone by arranging a sleepover in Abed’s dorm. ...

As a new semester gets underway at Greendale Community College, Jeff is the only member of the study group who doesn’t miss Pierce. But when their offensive friend unexpectedly returns after a summer spent getting in touch with his spiritual side & asks to rejoin the group, Jeff points out that there is no more room in the biology class they have all signed up for. & as Jeff argues that their friendships should be able to survive even without the structure of the study group, Abed struggles to find a new favorite television show. ...

When the members of Greendale’s Glee Club have a collective nervous breakdown after Jeff reports them to the government for copyright infringement, their director, Cory Radison, tries to convince the study group to fill in for them in the school’s Christmas pageant. Though they quickly reject his offer, Abed is entranced by “ Mister Rad’s” promise that the pageant would be a way to convince his friends to spend the holiday together. & although Troy is a Jehovah’s Witness & isn’t supposed to celebrate Christmas, Abed tells him that the pageant would be an opportunity to infiltrate the holiday & take it down from the inside. ...

Pierce tells the study group that he is expanding Hawthorne Industries now that his father is gone, prompting Britta to suggest that he invest in Shirley’s idea for a new sandwich shop in Greendale’s cafeteria. When Shirley’s ex-husband Andre proposes to her, Shirley tells Pierce that she is too busy planning their second wedding to concentrate on starting a business. Concerned that Shirley is abandoning her dreams in favor of getting married, Britta offers to plan the wedding for her, despite her negative views on marriage. When it turns out that she has a gift for wedding planning, Britta worries that she is destined to be a wife & mother. ...

Thanks to his new psychiatrist, Jeff is enjoying the benefits of anti-anxiety medication, including dramatically increased self-confidence. But as he wows everyone around him with his impressive charisma, Britta is concerned that his growing ego will overtake the rest of his personality. Meanwhile, Abed has started hiring celebrity impersonators to act out movie scenes with him in everyday life. & though he soon owes thousands of dollars to the talent agency, its owner Vinnie says he will forgive his debt if his friends agree to impersonate various celebrities at Howie Schwartz’s bar mitzvah. ...