When Jessica Alba landed a stripper's role in Sin City 2: A Dame To Kill For a decade after Sin City, she realised she had to seek additional help to get back in shape for her character.When Alba was approached to play Nancy Callahan in the film's second part by director Robert Rodriguez, she was careful about getting in shape as she had not only got married, but also had had two children during the gap of ten years."I was doing cardio dance classes with Jennifer Johnson and that's how I got introduced to her. When Sin City 2... came about, I asked her if she will help me get in shape for this movie. And thank god, she did," Alba said in a statement.Sin City 2: A Dame to Kill For reunites co-directors Robert Rodriguez and Frank Miller to bring the Sin City graphic novels back to the screen in 3D.The cast includes names like Bruce Willis, Eva Green, Joseph Gordon Levitt, Jessica Alba, Mickey Rourke and Lady Gaga. The film will release in 3D across Indian theatres September 5.