Deloris van Cartier has become a famous performer in Las Vegas since her time posing as a nun to hide from the mob. During her latest performance, she reunites with her friends, Sisters Mary Patrick, Mary Robert, and Mary Lazarus. They ask for her help, reuniting her with Reverend Mother, who explains that the convent nuns now work as teachers at the St. Francis Academy in San Francisco, which Deloris attended as a child. The school faces closure at hands of its administrator, Mr. Crisp, unless the school’s reputation can be improved. The nuns ask Deloris to reprise her persona as Sister Mary Clarence and become the new music teacher. Deloris reluctantly agrees.