The boys plan to have an all-guys weekend with their dad, but a surprise visit from their mom ruins it. When Kurt and Carey get a show on the ship, Mr. Moseby says they can stay on board, but worried their parents will permanently stay on the ship, the twins hatch a plan to sabotage their parents' show. Meanwhile, London tries to find the perfect belated birthday gift for Mr. Moseby by following him around all day. In the end, London makes Mr. Moseby very happy that he got a present from her because even his own mother forgot his birthday.

When the new aqua lounge is flooded, Mr. Moseby vows to expel the student responsible for the mess. Although Mr. Moseby assumes Zack is the culprit, Cody, Bailey (who had just returned from Kettlecorn), and Woody all believe they are each responsible for the disaster for different reasons. Meanwhile, Marcus leaves the ship to make a Broadway musical based on his hit song "Retainer Baby."

Mr. Moseby announces that London's dad, Mr. Tipton is selling the ship and that it will be dismantled within a week.