Ben Murphy (John Krausinsky John Krasinski) and Sadie Jones (Mandy Moore Mandy Moore) are a couple who love each other deeply, their love is full of romance and warmth, and it is only natural that they are about to enter the wedding hall. Sadie hopes to get married at St. Augustine's Cathedral, which has a deep relationship with her family, but it may be a bad decision. The Reverend Frank (Robin Williams Robin Williams) of this church seems amiable, but he is extremely demanding and strange. He was saddened by the fact that young men and women rushed into marriage and chose to escape, so Frank insisted that any couple who came to his church for a wedding should take a premarital preparation course. For couples who fail the course, Frank will have the right to cancel the wedding. It seems to be a routine business, but it is found to be full of obstacles in practice. Ben and Sadie, who have always had a smooth relationship, will face the biggest challenge before entering the church.