Deloris Van Cartier (Whoopi Goldberg) is a Vegas lounge headliner and girlfriend of a man with mob connections. She witnesses him commit a murder. She is assigned to a policeman, Eddie Souther (Bill Nunn), for protection. She goes into hiding in a convent under the name of Sister Mary Clarence. While in hiding, Sister Mary Clarence takes over the pathetic convent choir and develops it into a show choir. She also starts projects that clean up the local neighborhood. And because of the wonderful choir, the empty church services start filling up. The church even receives one very distinguished visitor. Deloris' ex-boyfriend sees her on the TV news and has her kidnapped. He wants her silenced because of her knowledge of the murder. However, the nuns in the convent follow her to Vegas and help save the day.