Jack and Eric are about to go to a club, when Jack meets a girl, Millie from 3B, in the hallway. They hit it off right away, and Jack decides to stay behind to show Millie the apartment, much to Eric's dismay. When Eric returns, he goes out on the balcony to say hi to Millie, who warns him not to get between her and Jack.
The next day, as they're stretching for a run up the Rocky steps, Eric expresses his concern over Millie. Jack thinks Eric's just jealous, and decides to blow off their plans to have breakfast with Millie.
That night, Eric is watching a horror movie when Millie enters, showing Eric the key Jack made for her. When she goes to the balcony, Eric tells Jack that there's something not right about Millie. Jack accuses him of trying to ruin his good thing.
Later, Eric catches Millie talking to Satan on the balcony. When Jack comes out, Millie slaps Eric and tells Jack he made a move on her. Jack gets angry, and Eric's had enough. He forces Jack to choose. "You're just my roommate," Jack replies, "Millie is much, much more thatn that." Millie then announces she's moving in.
The next day, Millie's creepy friends help move her stuff into the apartment. Eric warns Jack that Millie may be a witch. This only makes Jack more angry, anhen Eric leaves he talks to Shawn. Shawn also thinks Millie's a witch, so Jack decides to confront Millie. She admits the fact, but assures him that witch craft isn't what he thinks it is. Pacified, Jack decides to host Millie's Halloween party.
At the party, Jack becomes unsure of Millie's friends, who are all wearing matching black robes and chanting. Shawn is having a good time, however, and tells Jack to lighten up; but the good time is cut short when the brothers find themselves roped to the banister.
Millie reveals herself to be Ushkar, Queen of Malevolence. She tells Jack that she needed his balcony. It's a perfect place for the sun to hit a special crystal, which will create "Satan's Tail", sacrificing a Hunter and assuring the witches immortality.
The drama turns out to be for nothing, as Eric shows up, armed with sunscreen (spf 45 + zinc oxide) and Witchcraft for Dumb-Dumbs. He steps infront of the light beam, saving Jack and Shawn. Their plan foiled, the dejected witches are banished from the apartment.
Jack realizes he was wrong, and apologizes to Eric. Eric waves him off, saying they're friends, it's what friends do.
Later, Eric meets a girl, Sabrina, who may or may not be a witch, herself.
Meanwhile, Cory and Topanga have plans to go to Pittsburgh, to visit her parents. When Cory surprises her with plane tickets, Topanga reveals that she's afraid to fly. The plane is small and they are the only passengers, which makes Topanga even more nervous. When the pilot recognizes Cory as Eric's brother, and mentions Eric used to tutor him, Cory begins to fear for his life. He calls Mr. Feeny, who warns him not to get on the plane. Cory says it's too late. He tells Mr. Feeny he loves him, and says goodbye, prepared to meet his doom. When he hangs up the phone, however, he discovers the pilot has allowed Topanga to fly the plane, in order to alleviate her fear.