The study group meet on
Halloween in costumes to go to Vicki's party, with the exception of Pierce (
Chevy Chase), who has not been invited. Pierce calls Troy (
Donald Glover) as they are leaving, asking for help. Though Jeff (
Joel McHale) is reluctant, the group agree to go to Pierce's mansion, where he has locked himself in his panic room. Claiming to have done so accidentally and then saying it was because he saw his father Cornelius's ghost, he asks the group to search his house for the code. Jeff and Britta (
Gillian Jacobs) search together, with Britta attempting to make Jeff confront his issues with his father. In frustration, he eventually reveals that he has had his father's number for weeks but not called it. Meanwhile, Abed (
Danny Pudi) abandons Annie (
Alison Brie) after discovering a secret passage behind a bookshelf, leading Annie to become afraid, particularly after seeing Cornelius in a mirror. Abed finds a security room and concurrently watches
Cougar Town and the group's activities. After finding a sex dungeon, which Troy does not understand the purpose of, Shirley (
Yvette Nicole Brown) begins to worry about his new relationship with Britta, seeing Troy as too innocent. Abed finds surveillance footage of Pierce being watched in his sleep by an unknown individual. Jeff finds the notebook containing the panic room code, but the room he is in appears to be haunted, with knocking on the door with no apparent source, a picture of Cornelius distorting, and the room beginning to rattle. He finds Britta and leaves. They stumble across Annie, Shirley, and Troy, who have witnessed the outline of hands begin to protrude through a wall. Reaching the outside of the panic room, they find an image of Pierce unconscious. Pierce surprises them from behind, having tried to scare the group as he felt left out from the party. However, he locks the panic room in fear after Abed mentions the footage of an unknown figure he saw. The figure arrives and opens the panic room—it is Gilbert (
Giancarlo Esposito), Pierce's half-brother. After Cornelius' death, he arrived at the mansion and began discretely doing housework tasks out of loneliness. Pierce suggests that he move in, and the group departs. At home, Jeff calls his father. ==Production==