Ben, Aaron, Fitz and Riley are all clearly excited for Mardi Gras where they will be staying at Sara's parent's house. However, Sara tells them that they can no longer go because of a huge fight between her and her sister, Grace, over their grandmother's sapphire ring. Despite Sara's objections, the group reassures her that they will help her stay on her best behavior, and Sara agrees to go to Mardi Gras.
When they arrive at Sara's house the tension between Sara and Grace is obvious. Sara and Grace end up in a fight, and the group quickly leaves the house for Mardi Gras.
Aaron is clearly uncomfortable with the rowdy party scene of Mardi Gras, and Riley tries to get Aaron to loosen up with a drink. Ben suggests Sara patch things up with her sister by giving a heartfelt toast at Grace's baby shower tomorrow.
Back at the house, Ben has eaten the King Cake that Sara's mother baked for the Mardi Gras festivities. Unfortunately, Sara informs him that her grandmother's sapphire ring was hidden inside the cake and is now inside Ben's stomach. They decide Sara will bake another cake and Ben will try to get the ring with the help of some laxatives.
At Mardi Gras, Aaron has loosened up with the drink and tries to tell Riley how he feels about her. Riley gets distracted by Fitz calling her over for oyster shots. Aaron, in his drunken state, mistakes another girl for Riley, and they end up spending the night together. Meanwhile, Riley can't stomach the oyster shots, and Fitz ends up taking care of a vomiting Riley all night.
Ben wakes up the next day desperately needing to use the restroom due to the laxatives. However, Riley is still throwing up in the restroom, and Sara's father stalls Ben's search for another bathroom. Ben misses his chance to "pass" the ring and tries to remedy it by drinking an entire bottle of laxatives.
Meanwhile Aaron, who still thinks he slept with Riley last night, asks her how her night was. Riley's recount of her horrific night confuses and offends Aaron, who is under the impression that she is horrifically referring to sleeping with him last night.
Sara's mother and Grace run into Sara and Ben trying to bake another cake in the kitchen. When Ben admits he ate the cake, Grace still yells at Sara, and the two begin to fight again. The fight stops briefly when Grace, in a fit of anger, suddenly goes into labor.
Sara tries to help Grace give birth, but Grace, who is still angry at Sara, refuses to listen to her. Sara finally admits she is jealous of Grace and they make up. Grace brings the baby into the baby shower, and Sara and Grace are back to normal.
Ben interrupts the moment and declares that he has finally passed the ring. Now that the ring has traveled through Ben, neither Sara nor Grace insists on getting the ring anymore. Riley ends up taking the ring that started the entire fight between Sara and Grace in the first place.