In a slinky black lace number, and classic blonde curls, the 30-year-old could not be further removed from the characters that brought her into the homes of million every week - Hollyoaks’ Becca Dean and The Bill’s PC Sally Armstrong.
“I feel so lucky to be playing Roxie, there are just so many layers to her,” enthuses the bubbly actress.
“Bob Fosse’s choreography is immaculately clean and the script echoes that, it is so precise. It is really nice to be working with a script where everything is there for a reason, nothing is just thrown in.”
Having premiered on Broadway in 1975, Chicago has long been hailed one of the world’s greatest musicals. This current production opened in London in 1997, a year later winning the 1998 Laurence Olivier Award for Outstanding Musical Production.
Based on the play by Maurine Dallas Watkins, with book by Fred Ebb and Bob Fosse, music by John Kander and lyrics by Fred Ebb, Chicago tells the story of Roxie Hart.
A tale of murder, greed, corruption, exploitation, adultery and treachery, the piece, which is drawn from real life events in the roaring twenties, finds nightclub singer Roxie in prison for shooting her lover.
Along with Cell Block rival, double-murderess Velma Kelly, they fight to keep from Death Row with the help of smooth- talking lawyer, Billy Flynn.
“Being in Chicago really is a dream come true,” admits Bastian, who made the semi-finals of the BBC’s Strictly Come Dancing two years ago and has loved dancing since childhood.
“Dance is an art form that I have come in and out of all my life. As a child you’d find me dancing around the living room, putting on shows for my parents,” she laughs, “just making them watch me and generally being an irritating child.
“But I made a decision at the age of 12 to stick with the acting, although dancing remained something I loved.
“It came back into my life two years ago with Strictly, which rekindled my passion for it. I just fell in love with it all over again during that experience, especially ballroom and Latin.”
Famous for its slick choreography and minimalist setting - the band is on stage throughout, as are the cast - Chicago is proving the perfect vehicle to combine Bastian’s talents.
“From an acting point of view as well,” she emphasises, “the characters are just brilliant. They’re so well written and that makes them fun to play.
“Roxie and Velma are such really strong characters that it really is exciting to get on the stage each night and do this show.”
Bastian underwent five weeks intensive rehearsal to prepare for the role of Roxie, during which she was reunited with a couple of faces from her past - Stefan Booth, who plays Billy Flynn and Bernie Nolan, who plays corrupt prison warder Mama Morton.
“Tupele Dorgu [Coronation Street’s Kelly Crabtree], who plays Velma, and I went into rehearsals a week early, then the rest of the company joined us, which was exciting.
“Stefan and I worked on Hollyoaks together and go back ten years. “Funny, we’ve kind of been tailing each other for a decade - he left Hollyoaks, went into The Bill, then I left Hollyoaks and went into The Bill, but he’d already left. It’s really lovely to be working together again.
“And Bernie was on Brookside when we were on Hollyoaks, our Green Rooms were next to each other. Now I watch from the wings before I go on as she sings, and she is incredible.”
Chicago, Edinburgh Playhouse, Monday-Saturday, various times, £13.50-£35, 0844-871 3014