16 year old Joan Girardi is approached by someone claiming to be God. He gives her a mission, get a job. Will Girardi, Joan's dad and new chief of police for Arcadia, is trying to solve the case of a serial killer.

God wants Joan to score an ""A"" on a test about French saint Joan of Arc. As the teen hits the books, she draws comparisons to the life of the young heroine who claimed to hear divine voices and was burnt at the stake. Helen finds her daughter's newest obsession troublesome and urges Will to have the entire family visit a therapist. Meanwhile, Will is unjustly raked over the coals for shutting down a crack house.

After a summer of therapy and with school resuming Joan tries to return to a ""normal"" life even as she ignores God, who keeps reappearing; Will is sued for emotional distress by Andy Baker, whose drunk driving caused the accident that paralyzed Kevin; Luke and Grace try to adjust to their relationship.