After Agatha, a student at a Catholic college, jumps off the roof of a building, Gus drags Shawn to the school to investigate as a favor to an old teacher, Father Westley. Lassiter and Juliet are already there speaking with Westley and headmaster Father Bard, who explain that Agatha was a model student until three weeks ago when she suddenly started acting irrationally. Lassiter thinks it's murder but Shawn is leaning towards suicide. Father Westley has an alternate theory. He believes she was possessed. Father Westley is roundly dismissed, even by Father Bard, who explains that Westley used to perform exorcisms in the past, something the Church now looks on with skepticism. But Westley is insistent and Gus agrees to take the case, over Shawn's objections.