In the twilight world of gangsters and their molls, Nathan Detroit is losing his grip on the institution of the floating ‘crap game’ (the dice gambling scheme he runs that switches venue to avoid detection by the local police) and desperate to find the money to pay for the only location he can currently get his hands on. To seal the deal and quell the tempers of the gangsters who are gathering in town and keen to ‘shoot crap’ he bets his buddy, Sky Masterson, a thousand dollars that Sky will not be able to take a local Salvation Army girl, Sarah Brown, on a date to Havana.
Meanwhile Nathan, engaged for fourteen years to cabaret artist Miss Adelaide, is struggling to keep her demands for marriage at bay, whilst she continues to battle with the symptoms of an incessant psychosomatic cold that plagues her as she is waiting to walk down the aisle.
Sarah isn’t taken in by Sky’s obvious charm and brushes off his advances until it becomes clear that her struggling Salvation Army mission will be closed down by General Cartwright if it doesn’t prove itself to be more successful in attracting the local population of ‘sinners’. Since Sky has promised her that one dozen of his.
Comrades will show up at a forthcoming prayer meeting, she is convinced to travel with him to Cuba where, under the influence of alcohol, her defences slip and they realize they are falling in love with each other. On returning to New York, Sarah discovers that, unbeknown to Sky, Nathan and his buddies have been using the empty mission as a site for the crap game. Sarah feels duped and Adelaide is furious that Nathan can’t give their relationship priority over his gambling habits.
At a crap game held in the sewers of New York, Sky bets all the members of the floating crap game that if he wins his roll of the dice, they will have to go join him at the mission to repent their sins. After winning his bet, and after Sarah & Adelaide plot to reform their respective lovers after marriage, the mission is saved by a successful prayer meeting led by Nicely’s gospel-like confession and the couples tie the knot in a joyous double wedding.