Unlike the play, the movie opens up by going offstage for flashbacks to their affair, but the flashbacks are notable mostly for the way they focus on the theatrical lives of this couple - the way their private lives seem valid only to the degree that they reflect acceptance from the audience.
Sheila was a star, but now she simply needs a job. They met in the theater, courted in the theater, broke up because Zach's job left no time for a personal life. An unexpected dancer has appeared for the auditions - Sheila ( Vicki Frederick), Zach's former girlfriend. Meanwhile, a backstage drama is taking shape. Many of the dancers have the most extraordinary difficulties in doing this, and one of them is frank: "Give me the lines, and I can play anybody. Finally there are 16 left, and Zach asks each one of them to talk on a personal level - talk about when they were born, and where, and what their lives have been like, and what their dreams are. Platoons of dancers are brought on stage, winnowed, dismissed. Well, if that isn't the life they wanted, why did they volunteer for it? They step hesitantly to the edge of the stage, blinded by the spotlight, and talk into the void. Occasionally he lights a cigarette, and the ash glows as he takes the measure of the dancers on the stage. Zach ( Michael Douglas), the choreographer, sits behind a writing platform somewhere out there in the darkness. Most of the scenes take place inside a theater. The result may not please purists who want a film record of what they saw on stage, but this is one of the most intelligent and compelling movie musicals in a long time - and the most grown up, since it isn't limited, as so many contemporary musicals are, to the celebration of the survival qualities of geriatric actresses.
Richard Attenborough's film treatment of this story sticks to the outlines of the stage version, by and large, although he leaves the stage to fill in the details of the choreographer's old romance, and he leaves out some of the original songs to make room for some new ones. A choreographer is casting eight dancers for a new musical he hopes to stage, and during one long and truthful day he auditions dozens of dancers before he makes his final selection. "A Chorus Line" is now in its 11th year on stages all over the world its story is by now well-known.