Bart is given the role of a cooper in the school's medieval festival, while Lisa is the queen. Bart is blamed and expelled when rats come out of large pie that is presented to the queen. Marge looks for a new school for Bart and decides to try out a Catholic school.
In his first day at school Bart encounters a tough nun and Father Sean. Bart takes a liking to Father Sean and begins to embrace the Catholic faith, which concerns Homer and Marge. Homer goes to the school with the purpose of taking Bart out of school, only to himself being converted before the night is through. With her husband and son gone Marge finds herself alone at church.
Reverend Lovejoy tells her that when they die she and Homer will be going to different heavens. Marge, Ned and Reverend Lovejoy go to Homer and Bart's first communion class to at the very least liberate Bart from becoming Catholic. To bring Bart back to his old religion they take him to a religious festival. Father Sean and Homer arrive hoping to take Bart back, but Bart in one his rare moments of insight brings both sides together, that is until 1,000 years later.