A cool story I had kinda heard about. The Finnish group Nightwish had been having trouble with their lead singer who good but not great. They were in Denver in 2012 and she got real sick. The group who opened for them was Kamelot and they had two female lead singers
They gave the crowd a choice. Cancel the concert and refund money. Or have the crowd sing many of the songs plus have the two female singers do their best. The crowd voted the later. One of the singers sort of knew some of the songs as she had auditioned a while back. The other knew none of the songs. They had 55 minutes to learn the show as best they could. They were given sheet music to take on stage.
A very memorable show for the fans.
The next show on tour was in Salt Lake City where the regular singer did the show. They asked a Finnish singer Floor Jansen to fly in and learn the show for Seattle in 48 hours which she did. They fired the regular singer.
https://youtu.be/zH33rNy33iU?t=526Nightwish - The Denver Debacle (2012)
Elize Ryd & Alissa White cover for a sick Anette Olzon during a concert at the Ogden Theater in Denver, CO, 2012.
This video is a collection of multiple videos, to recreate the concert and tell a story of the event.