On her parents' 30th wedding anniversary, florist Sadie Jones (MANDY MOORE) is both surprised and pleased when her boyfriend, Ben Murphy (JOHN KRASINSKI), proposes to her. Her parents are a little concerned, especially since their other daughter, Lindsey (CHRISTINE TAYLOR), has moved back in with them after her divorce.
Yet, Sadie is determined to make it work, and thus convinces Ben to take a wedding preparation course at her childhood church run by Reverend Frank (ROBIN WILLIAMS). Along with his young helper, Choir Boy (JOSH FLITTER), the minister put prospective couples through the paces in something of a pre-marital boot camp. During the next three weeks, the two learn things about each other, such as Ben seemingly not liking Sadie always turning to her childhood friend Carlisle (ERIC CHRISTIAN OLSEN) for advice, while Ben's friend, Joel (DeRAY DAVIS), thinks the whole thing is crazy and warns him about the pitfalls of marriage.
With Reverend Frank determined to make sure the couple has what it takes to have a happy marriage, Sadie and Ben must put up with his unorthodox tests, eavesdropping and more, all of which threaten to break up their relationship.