On the way to a Halloween party, the study group must free Pierce from his panic room and slowly comes to suspect that his mansion is haunted.

Troy worries about losing Abed to a fellow Inspector Spacetime fan at a convention for the show, while Annie fantasizes about being married to Jeff.

The study group contends with a group of German students who take over the study room. Chang makes his return to campus.

Britta joins Jeff to see his estranged father on Thanksgiving. Shirley invites the rest of the group to spend the holiday with her judgmental in-laws.

Greendale comes together to get to the bottom of Chang's amnesia, which Abed films as a documentary. Jeff, however, suspects Chang is faking it.

Dean Pelton enlists the study group to beautify the campus to woo a wealthy student to Greendale. A class on teaching P.E. pits Shirley against Troy.

Jeff sets out to embarrass Britta when she announces a dance for women's empowerment. Abed dreams of shuttling between two dates in one night.

Dean Pelton prompts the study group to use puppets to relive the traumatic events of a recent adventure.

Jeff organizes a lovely holiday gathering at his apartment, but Annie secretly invites Professor Cornwallis to get in his good graces.

When Annie and Shirley learn that Leonard is actually holding the spot as the class valedictorian, they join forces to bring him down.

Abed's research into the study group's history uncovers an overlooked series of chance encounters that led each of them to Greendale.

A plan to celebrate Jeff's early graduation is unexpectedly disrupted by the study group's evil doppelgangers from the Darkest Timeline.