Based on the play by Philip Barry, a young man engaged to a wealthy woman wants to quit working and finds a kindred spirit in his fiancé's sister.
Johnny Case (Cary Grant) returns from vacation and tells Nick Potter (Edward Everrett Horton) and Susan Potter (Jean Dixon) that he found a wife. Johnny goes to Julia Seton (Doris Nolan) and finds a palace, learning she is rich. Julia says he will make millions, but he says no. Julia tells her sister Linda Seton (Katharine Hepburn) how they met and tells her father Edward Seton (Henry Kolker) in church that she is going to marry Johnny. Linda invites Johnny to the play room and says her alcoholic brother Ned (Lew Ayres) could have been a musician except for their father. Linda says she is not happy. Johnny is tired of working for money and wants to take off. Ned plays piano, and Julia complains about Johnny's tie. Linda says that Johnny is life and offers to give a party. Edward wants to know more about Johnny and learns he worked his way through Harvard after his father died; but he delays approving the wedding until Julia asks him.
Linda is happy; but Edward gives a formal party. Ned gets drunk and tells Johnny about the family. Nick and Susan find Linda in the play room. Julia tells Johnny to get Linda to come down; but Linda gets Johnny to stay. Johnny is glad to see Nick and Susan, saying he can quit his business soon. Stuffy Seton Cram (Henry Daniell) and Laura Cram (Binnie Barnes) come in. Seton says Johnny has made his stock go up. Edward and Julia find Johnny and Linda doing acrobatics. Edward reprimands Linda and urges her to travel, and he offers Johnny a position at his bank. Johnny says he wants to quit; but Julia asks him to make money for a year first. Johnny stays with Linda, and they waltz. Linda encourages Johnny's dreams, and they kiss at midnight on New Year. Linda sends him to Julia and drinks with Ned, saying she loves Johnny. Edward announces the engagement. Linda goes down but finds Julia upset that Johnny disappeared.
Linda looks for Johnny and calls on Nick and Susan. They learn that Julia will not sail with Johnny. Linda urges Julia to do so; but Julia says Johnny won't go. Linda argues with Julia and their father that Johnny is right. Ned tells Linda that Julia is dull. Johnny arrives and says he will take the bank job. When Edward plans their honeymoon with business and their house, Johnny changes his mind and says he is leaving. Linda sees that Julia does not love Johnny. Linda asks Ned to sail with her; but he can't, and Linda says good-bye. On the boat Nick and Susan are glad to see Johnny and then Linda too.
This comedy borders on tragedy as Johnny almost succumbs to wasting his life making money like the alcoholic Ned; but he is rescued when he meets another free spirit like himself.