A young woman named Julianne discovers that her long-time friend Michael, whom she harbors feelings for, is engaged to a wealthy twenty-year-old named Kimberly. Julianne recalls a pact she made with Michael years ago: if they were still single by the time they turned 28, they'd marry each other. With the realization that she is in love with Michael and seeing her chance with him slipping away, Julianne decides she must sabotage the wedding and win him back. She heads to Chicago under the guise of being happy for Michael’s upcoming nuptials, but with the secret intent to break up him and Kimberly.

Upon her arrival, Julianne's plans are met with unexpected complications. She is asked to be the maid of honor, and as she takes on this role, she starts embedding herself into pre-wedding activities to execute her covert mission. Michael seems completely smitten with the sweet and seemingly perfect Kimberly, and Julianne's antics to dissuade him bring her closer to Kimberly, making her task more emotionally challenging. As the wedding approaches and her tactics escalate, Julianne risks not only her friendship with Michael but also starts to question her own values and feelings, leading to a series of comical and poignant misadventures.