"My Best Friend's Wedding" is centred on the relationship between lifelong friends Julianne "Jules" Potter (Roberts) and Michael O'Neal (Dermot Mulroney), who had a pact to marry each other if they were both still single by their 28th birthday. Weeks before she turns 28, Michael calls her to tell her he's engaged to Kimmy Wallace (Cameron Diaz). Jules comes to the realisation she is actually in love with Michael, and attempts to sabotage his and Kimmy's wedding, but things get more difficult when she's appointed maid of honour.