Sabrina is fed up with her friends' unenthusiastic attitudes towards Halloween so she plans for them to go on a Halloween Murder Mystery Train. But she doesn't realize it's a magical train that turns them into their characters: Sabrina as the detective; Harvey as 'Biff Buffington' - tennis champion; Morgan as an English countess; Roxie as Hortense, the countess's maid; Miles as a foreign professor and Josh as a photographer. And Josh is the murder victim.
Sabrina and Roxie get their own call in college radio show. Sabrina is tongue tied while Roxie takes right to it. Sabrina then bows out and lets Roxie have the show.
Josh gets Sabrina a job at the newspaper, but she wants to keep their relationship a secret so people don't think she got the job as the photographer's girlfriend.
When Sabrina tries to say "I Love You" after Josh professes his love, it comes out in a funny voice. The Love Doctor says that she has to tell him that she is a witch.
Great-aunt Irma shows up with a witch named Peter that Sabrina is supposed to marry immediately. Peter doesn't want to get married and falls for Roxie.
Sabrina is annoyed when Josh says that women can't play tennis so she gets professional and magical help. Zelda and Hilda coach Amanda for her witch's license.