Act One

Michael Dorsey, a struggling actor, is fired after causing a scene during rehearsals in a show directed by Ron Carlisle. Due to his demeanor, he is unable to get any other parts ("Opening Number"). While closing up the steakhouse they work at, Michael complains to his roommate, Jeff Slater, that nobody wants to hire him. Since it's Michael's 40th birthday, Jeff decides to read him the bucket list he made when he was 19, reading off everything Michael swore to accomplish in 20 years. Michael, angered by this, thinks about how little he's accomplished ("Whaddya Do"). Sandy Lester, Michael's neurotic ex-girlfriend, arrives at their apartment for his birthday and immediately starts bemoaning about how terrible her life is. Michael, expecting a party, arrives and is surprised by Sandy and Jeff. After thanking them, Sandy gets Michael to help her with her audition for the musical Juliet's Curse. She panics about all the things she knows will happen at her audition ("What's Gonna Happen").

Michael goes to his agent, Stan Fields, and demands to know why he didn't get called back. They argue. Stan tells him that he is incredibly hard to work with, and that he will never work again. Michael storms out, desperate for a job. But while looking through Sandy's script, he gets an idea ("Whaddya Do Reprise 1"). At the auditions, women are auditioning for the role of the Nurse but are all getting turned down. When it's finally Sandy's turn, she refuses to stop singing the moment she gets turned down but eventually gives up and leaves. Dorothy Michaels (Michael in disguise) enters and humbles the producer Rita Marshall. He sings the audition song and is hired by Ron and Rita ("I Won't Let You Down"). Michael, still dressed as Dorothy, meets Jeff at the steakhouse and reveals himself. Jeff tells him that what he is doing is stupid and incredibly harmful and asks what he will tell Sandy, since he landed the role she wanted. Michael says they won't tell her and talks about his plans with Dorothy. The next day at rehearsals, Michael (as Dorortyh) witnesses the mess of a show that is Juliet's Curse . He meets the dimwit reality star winner of Race To Bachelor Island , Max Van Horn, who was cast as Romeo's brother named Craig. He also meets the actress starring as Juliet, Julie Nichols. They perform the song of Juliet celebrating her survival, choreographed by Ron Carlisle ("I'm Alive").

After the show, Julie and Dorothy have lunch together. Julie tells Dorothy about her dreams and about how she chose them over a relationship, and she'd do it again ("There Was John"). Dorothy and Julie agree on a way to make the show better. After a few days at rehearsal, Dorothy improvises getting Craig to fall in love with the Nurse instead of Juliet. Ron is infuriated with this, but everyone in the team sides with Dorothy, including Rita. She lets Dorothy lead the show. Everyone is extremely happy with the changes and having Dorothy as their new leader. Rita changes the show's name to Juliet's Nurse ("I Like What She's Doing"). After the show, Dorothy and Julie head back to Julie's apartment. As Julie talks about herself, Michael is realizing that he is in love with her ("Who Are You").

Michael heads back home to tell Jeff about his day with Julie, which is interrupted by Sandy at the door. She asks Michael where he's been and tells him she's been devastated about not getting the part. After a small tangent of how horrible her life is, Michael promises to have dinner with her to make it up to her. She agrees to it, but panics knowing that something will go wrong, and Michael will probably stand her up ("What's Gonna Happen Reprise"). She leaves. Jeff tells Michael that what he's doing is ridiculous, and he won't be able to get away with it without hurting people. Michael is too blind to understand this; he disagrees and says Dorothy will be successful and around forever ("Unstoppable"). Still daydreaming about his success, he runs into Julie as Dorothy and kisses her on impulse, scaring Julie off.

Act Two

Back at his apartment, Jeff sums up and mocks Michael's recent mishaps ("Jeff Sums It Up"). Michael gets a call telling him that the cast is going to see Julie sing at a bar, so he decides to go and meet Julie there as himself. Julie sings a song about her feelings towards Dorothy ("Gone, Gone, Gone"). After the song, Michael catches Ron's attention and discovers that he's taking all the credit for Dorothy. Even more motivated to talk to Julie now, he goes up to her and tries to flirt, which results in her throwing wine in his face. They go back home, and Jeff makes fun of him, when they're interrupted again by Sandy. She yells at Michael for standing her up, but before leaving, she informs them about Dorothy getting the role and how annoying she is. Michael tells her that she shouldn't be envious of another woman's success. Sandy says no and leaves.

Michael decides he will go over to Julie's as Dorothy and have Dorothy be honest with her. At Julie's apartment, Ron is trying to get Julie to date him while Julie rejects him every time. Dorothy comes, and Julie lets her in. Ron blames Julie disliking him on Dorothy, who comes to Julie's defense. After getting Ron to leave, Julie tells Dorothy that she has feelings for her and wants to pursue them. Dorothy quickly rejects her, upsetting Julie, who thought they had started something special ("Who Are You Reprise"). Michael heads back home. While undressing, he hears Max singing for Dorothy outside ("This Thing"). After he is yelled at by a neighbor twice, Michael relents and lets him in. He proclaims his love to Dorothy through a ballad and an infected tattoo of her face on his chest. Jeff walks in on them. Max attempts to fight him but is told to leave by Dorothy.

After getting him to leave, Michael finally sheds himself of Dorothy and tells Jeff about his day. After proclaiming that this couldn't get any worse, Stan comes in. He tells Michael that he has booked a role in a play. Michael tells him he is unable to take it because he's doing Jeff's play. Stan tells him that it's the worst decision he's ever made in his life and leaves. Michael decides he wants to try and fix things with Julie again ("Whaddya Do Reprise"). But while half dressed as Dorothy, Stan comes back and walks in on them. Stan tells him he'll be scorned nationwide and fires him again. The next day, the cast and crew are celebrating opening night ("The Most Important Night"). Before the show in Dorothy's dressing room, Rita congratulates and thanks Dorothy for her impact on the show, extending her contract another year as an opening night gift. Dorothy tells her to pay Julie the same as Max and she will take it. After Rita leaves, Max enters. Max thanks Dorothy for believing in him when he had always felt different from everyone else. Dorothy tells him that he doesn't need help and to trust in himself. After Max leaves, Julie walks in to leave a note and tells Dorothy that she has never been anything but honest to her. Julie then tells Dorothy that she means a lot to her and loves her, but they probably shouldn't see each other anymore. Alone, Michael reflects, begging Dorothy to show him what to do next ("Talk To Me Dorothy").

Dorothy and the cast are now performing the finale for Juliet's Nurse ("Arrivederci!"). Dorothy interrupts the song as Nurse, and begins improvising, with Max joining her as Craig halfway. Julie, out of character, stops her and asks what she's doing. Michael reveals himself. Everyone on stage, including Rita and Ron, are shocked. Julie is at a loss of words and runs off.

Sandy returns to their apartment in a frenzy. She and Jeff fight over Michael's influence on her and Jeff's writing stagnancy until Jeff hits on her, and they realize they are attracted to each other. Just as they are about to kiss, Sandy panics about how what they're doing is a bad idea but is cut off by Jeff kissing her ("What's Gonna Happen Reprise 2"). They run off into the bedroom. Michael comes home the morning after, and in between his regret, realizes how creating Dorothy widened his empathy towards the women in his life. He apologizes to an emerging Sandy for obstructing her chances with the show. Sandy admits that idealizing Michael was hindering her self-confidence and potential future alongside Jeff, who hands Michael a play penned from the experience. Michael wonders if Julie will ever speak to him again ("Michael's Reprise"). Later, Michael meets Julie at the park, awkwardly apologizing. Julie at first retorts that he has harmed everyone in the production. When she relays the vast disappointment and bias that women experience, Michael vows to truly listen to her. She gently concedes that Michael truly staked his pride to perform, but she misses Dorothy. Michael offers a better, forthcoming connection from what they shared before. They silently move back to a bench, tentatively beginning to rebuild trust. ("Thank You").