As the sun sets on the beautiful Mexican coast, Charlie Gordon's reckless tendencies lead him into an unforgettable adventure. He convinces his brother-in-law, Herb Sullivan, to join him on an all-expenses-paid luxury cruise, courtesy of Holland America. However, Charlie strategically omits the crucial detail that their so-called "vacation" comes with an unusual twist: they must work as dance hosts. As a result, the duo must trade the comforts of their cabin for the cramped quarters of the ship's bowels. To make matters worse, failure to perform could result in financial disaster, with initial estimates of a $3,000 tab, later revealed to be closer to $5,000, or facing expulsion from the ship.
Under the strict supervision of cruise director Gil Godwyn, a former military brat turned song-and-dance man, Charlie and Herb struggle to maintain their charade, hindered by Charlie's clumsy dancing skills. Throughout this bizarre experience, both men encounter enticing female companions. Charlie finds himself drawn to Liz LaBreche, an heiress whose enchanting beauty masks her financial struggles - her wealth is merely an illusion. Meanwhile, Herb becomes infatuated with Vivian, a charming widow and ex-book editor who, unaware of his true job, seeks to reignite her social life with her daughter and new husband by her side. However, Herb's lingering love for his late wife, Susie, complicates his feelings for Vivian, prompting him to stand her up during a planned solar eclipse viewing.
Oblivious to Liz's deceptive financial situation, Charlie initially believed that pairing himself with a wealthy woman would secure his future. As night falls, Charlie's unconventional pursuit culminates in a hilariously awkward dance display with Mrs. Carruthers, much to the delight of the ship's owner. Taking advantage of this unexpected success, Charlie devises a scheme to feign a romantic encounter between Gil and Liz, hoping to have the night to himself with her. Under the rare celestial phenomenon of an eclipse, Charlie seizes the moment to propose to Liz, planning an impromptu wedding. However, Liz's mother sees dollar signs in her daughter's potential match, while Liz, having developed genuine feelings for Charlie, is conflicted about the relationship.
Their love story takes a downturn when Gil discovers Charlie's ruse and confronts them, leading to a painful rejection from Liz. As the trio hastily departs the ship, Herb contemplates his feelings for Vivian. It isn't until Charlie reminds him that Susie was always "his" sister before being Herb’s wife that he realizes he must act on his emotions. Ultimately, both men come to terms with their feelings for their respective partners and resolve to pursue them.
In a thrilling turn of events, as they prepare to launch a lifeboat, Gil shows up, prompting Herb to confront him for the first time with a strong rebuke. This outburst leads to Gil's dismissal by Mrs. Carruthers, who labels him an "asshole" and replaces him with another dance host. As chaos unfolds, Herb and Charlie find themselves on the brink of a plane takeoff, signaling for everyone to return and catching Vivian's eye with a story Herb once told her.
In the midst of this turmoil, the revelations of their elaborate schemes spill out. While Charlie and Liz continue their dating romance—Charlie even scores a significant poker win against a rich opponent—Herb finds a path back to Vivian. Together, they navigate the intricacies of love and relationships, ultimately finding happiness on their tumultuous journey.
