The Peeples are an affluent East Coast family celebrating their annual Moby Dick Day reunion at Sag Harbor in the Hamptons. The weekend is interrupted when Wade Walker (Robinson), the fiancé of Grace Peeples (Washington), shows up to propose after being goaded by his brother, Chris (Malcolm Barrett).
Upon arrival, Wade loses his wallet while being chased by the family dog. At the grocery store, he sees Grace’s father Virgil (David Allen Grier), a judge, talking to a woman later revealed to be the mayor. He also sees Grace’s sister, Gloria (Hawk), with her lover, Meg (Lewis-Davis), who is not known to the family. Wade learns more about Grace, including about her ex-boyfriends, breast implants, and mother. Grace’s mother, Daphne (S. Epatha Merkerson), is a former singer and recovering alcoholic. Wade attempts to propose at dinner, asking everyone to say what they love about the people in their lives. This ends abruptly when Virgil says he had to pay for Wade at the store.
Wade goes to see Virgil play at a club but discovers he is not there. In the park near the beach, Wade encounters a group of nudists, which includes Virgil. At the guest house, Wade confronts Grace about her implants, and she is honest. They play “naughty school girl”. Virgil peeks through the window and runs off in disgust.
Wade discovers that Grace’s musician brother, Simon (Tyler James Williams), is also a thief. While playing through the Peeples’s house, Wade finds Daphne’s headpiece from her days as a performer and begins to sing while wearing it. He is caught by Virgil. Chris shows up unexpectedly to “help” Wade propose. Because of Chris’s borrowed Gamma Phi sweater, Virgil thinks they are fraternity brothers and invites him to stay.
At Nana Peeples’s (Diahann Carroll) house, Wade gets Daphne to sing, while Virgil watches in disgust. Chris makes advances towards Gloria, angering Meg. Back home, Daphne discovers her expensive earrings have been stolen. Virgil believes Wade is the thief. Wade and Chris are at the bar, where they see Simon talking to an uninterested woman. They follow him into the bathroom and pretend to be thugs, but then tell him to return his mother’s earrings and stop stealing. Chris returns to the guest house to find Gloria, while Wade finds Virgil in a sweat tent and tries to bear it for Grace’s hand in marriage. Wade ends up burning the tent down.
At the Moby Dick Day celebration, Grace tells Wade he looks terrible and offers him a drink from a thermos with a mushroom drawn on it. The mayor confronts Wade. While Virgil is giving a rendition of Captain Ahab, Wade hallucinates that Virgil is talking to him and charges at him with a harpoon. Wade is knocked unconscious.
Wade wakes up and is insulted by Virgil. Wade wants to head back to New York with Grace and Chris, but Grace wants to stay with her family. Wade and Chris leave. After the brothers depart, Virgil admits he has been swimming with the Humpback Whale non-sexually, Gloria and Meg tell everyone about their relationship, Simon admits to his stealing, and Daphne admits she put mushrooms in her drinks. The dog returns Wade’s wallet, and Simon takes Wade’s engagement ring out of his pocket.
Grace falls into her mother’s arms, realizing Wade was telling the truth. She returns to New York a few days later, without being able to contact Wade. She sees his schedule book and meets him at a kids’ museum. Grace apologizes and proposes to Wade. He proposes to her in return. Virgil arrives to accept Wade into the family, and the entire family joins Wade on stage to perform for the children.