The gang returns to Greendale after their winter break. Jeff worked out his back muscles, Annie did some volunteer work, and Shirley spent time with her ex-husband. Everyone's interested in the new guy Annie doesn't seem to want to talk about; when Shirley tries to talk about her ex, no one's interested in him. Then, during their catch-up session, Chang appears out of nowhere, demanding to know whether or not he can join the study group. When Jeff renders an unfavorable verdict, Chang agrees to let him sleep on it, think about it, and then get back to him.
While the class waits for Professor Duncan to arrive, Britta grills Shirley on why she'd date her ex-husband who cheated on her with a stripper. Troy accidently confides in Pierce that he's relieved Shirley's not dating Chang after what happened on Halloween. Once Troy spills that Chang had sex with Shirley, Pierce makes him elaborate on how and what he knows. Troy makes Pierce promise not to tell anyone. When Duncan arrives to class, he apologizes, explaining that he's now sober and had a difficult time finding the school.
Rich arrives late to class. Sitting right next to Annie, he tells everyone about volunteering with her over the holiday break. Everyone, including Jeff, realizes Annie's new crush is Rich. At lunch, Annie asks the gang to consider letting Rich into their study group. Since Anthropology class may be much tougher this semester with a sober Duncan, they may need Rich's smarts to get them through. Jeff immediately counters Annie's suggestion. Annie suggests holding an open mixer later that night, inviting all possible study group candidates. This way, the candidates can plead their case and the group can make an informed, democratic decision.
Shirley's ex-husband/boyfriend stops by Greendale to spend the day with her. The gang isn't silent about their feelings toward him or the situation, especially Britta. Shirley quickly shuts everyone up, telling them she's a grown woman who makes her own decisions. Oh, and she's pregnant. In fact, she's eight weeks along. Troy and Pierce quickly do the math and realize eight weeks ago was Halloween.
Annie welcomes the students from Anthropology class to the study group mixer while Troy and Pierce strategize a way to ask Andre if he slept with Shirley right after Halloween. When Pierce suggests they come clean with Shirley about sleeping with Chang and let her deal with it, Troy disagrees. Jeff shows up at the mixer with a possible study group candidate, a new female bombshell. Troy lets Jeff know that there are a lot more important things going on than his shameless lobbying, but when Rich arrives with large bags of kettle corn he makes in his garage, Troy's immediately distracted.
Chang shows up at the study room, wondering why everyone from Anthropology class is there. He soon realizes the group is opening up his study group slot to all comers. When he sees things going in Rich's direction, Chang makes a last-minute deal with Jeff. Back in the study room, Annie pleads her case for Rich. Then Jeff makes a speech in favor of Chang and calls for a vote. It's three against three, and Shirley is the deciding vote. When Shirley votes in favor of Chang, Pierce lets the cat out of the bag, telling everyone that Chang and Shirley had sex on Halloween. Everyone's stunned, including Chang and Shirley. Troy explains that Chang left him a message Halloween night about the incident.
Chang pulls up photos from Halloween on his phone and finally realizes what they are. When he shows Shirley, she asks him to leave. But Jeff reminds that they just voted Chang into the study group. Rich packs up his kettle corn and leaves, followed by Andre. Annie confronts Jeff in the bathroom. He can't continue to sabotage her dating life; he either wants her or he doesn't. After Annie leaves to find Rich, Britta walks into the bathroom, asking for Jeff's help. Shirley's devastated. Jeff has to find Andre and convince him to stay with Shirley.
Finding Andre outside the library, Jeff tries to school him, but winds up learning from him instead. Andre tells Jeff that he's mad at himself; if he didn't leave Shirley in the first place, none of this would have happened. The important thing is that he's going to be a dad again, whether it's his baby or Chang's. When Andre leaves to find Shirley, Abed joins Jeff. He tells Jeff that Annie asked Rick out, but he said no because she's too young.
After hearing that Rich turned Annie down, Jeff takes off running through the rain. He shows up drenched at Rich's front door asking for help - how can he appear good to help him get away with being bad? Looks like the birth of an unlikely friendship...