The show features stage and TV stars John Partridge as Billy Flynn and Hayley Tamaddon as Roxie Hart, with X Factor winner Sam Bailey as prison matron Mama Morton.
The show is based on real-life events back in the roaring 1920s. Nightclub singer Roxie Hart shoots her lover.
Along with her cell block rival, double murderess Velma Kelly, they fight to keep from death row with the help of lawyer Billy Flynn.
Sam, who won The X Factor three years ago, said: “It’s going really well. It’s a great role to play. I’m having fun with it.
“I’ve never done acting before and I’m having quite a lot of fun playing this role.”
She worked as a prison officer at HMP Gartree in Leicestershire for three years but said: “It’s no comparison.
“Prison back in the day was quite a lot different.
“Mama Morton does favours for money but nothing like that ever happened on my watch.
“The clothes she wears are quite revealing and you’d never get away with it, especially in a men’s prison. You’d be called into the office and told to cover up.”
Sam does miss the job, though, despite her new, glamorous life.
“I miss the colleagues and togetherness of the staff and I miss doing good, when you see people change for the better. There’s some that don’t.”
She said of Mama Morton: “She thinks she’s sexier than she is. She’s a character that looks after her girls.
“Everyone’s got a lot of respect for her. No-one messes with her.
“She has got a dark side but she’s got a heart in there as well. There’s certain parts where she shows a glimmer of that heart.
“It’s a great role to play. There’s so many different sides to her character.”
She’s enjoyed getting to grips with acting but admits to being terrified too. “When I got the job I went to the first day where you meet everybody and I went to the toilets and I was trying to work out a way of blagging an illness so I could go!”
After only a short introduction, Sam found to her horror that rehearsals were starting. “Literally, you couldn’t get more plunged into the deep end than I was.
“I had no preparation but I learned so much and came along so much.”
Chicago is at the Lyceum from Monday, June 6 to Saturday 11. Box office: at the Crucible, call 0114 249 6000 or online at Sheffield Theatres