The film tells the story of Doug Harrison, played by Josh Gad, who is about to get married but faces a thorny problem: there is no suitable best man. As his wedding with his girlfriend (played by Kaley Cuoco) approaches, Doug seeks the help of Jimmy Callahan (played by Kevin Hart), whose company specializes in providing services for people who can't find a best man. In the process of preparing for the wedding, Doug and Jimmy staged a hilarious story.