In turn of the century San Francisco, Tony Angelo runs the Barbary Coast's most successful saloon, which features his sweetheart, singer Sally Templeton. One night, Tony is enjoying his duties as host when a young girl named Katie Flanagan arrives and asks for her uncle Pete. Katie, who has just gotten off a boat from Ireland, is devastated when Sally and Tony inform her that her uncle is dead, and becomes even more despondent when Tony decides to send her back to Ireland on the next boat. Upon hearing that Katie has no family left, Sally insists that she at least be allowed to stay the night. Tony acquiesces, and soon after, Katie's earnest charm wins his affections and convinces him to allow her to stay for a few months while the boat first journeys to Seattle. Katie happily settles into life at the Gold Coast, Tony's saloon, although she insists that Tony take her to church. Knowing that Katie is expecting a proper Catholic church, Sally instructs Tony to take her to the fancy church on Nob Hill. Although Katie is awed with its magnificent houses, Tony tries to explain to her that the snobbish Nob Hill residents do not mix with their kind. His words are disproven, however, by the friendliness of Harriet Carruthers, the beautiful socialite who made Katie's acquaintance on the boat. When Harriet brings her brother Lash, who is running for district attorney, to the Gold Coast, Sally grows uneasy about Harriet's attentions to Tony. Sally's fears deepen after Tony and Katie dine at Harriet's mansion and Katie tells Sally that Tony kissed Harriet. Tony brushes aside Sally's jealousy and announces that he is backing Lash in his election bid, despite the worries of his fellow saloon owners, who fear that Lash will close them down. Although Katie loves Sally, she approves of Tony's growing infatuation with Harriet, for she wants to live on Nob Hill. Harriet's overt flirtations drive Sally to work in another saloon, and Tony conceals the truth about her disappearance from Katie. Tony campaigns hard for Lash, and on the night Lash is elected, goes to the Carruthers mansion to celebrate. Tony's hopes for a life with Harriet are crushed, however, when Lash offers him a large sum of money for his help and Harriet states that while she is fond of him, their worlds will never mix. Dejected, Tony returns to the Gold Coast, where his former friends tell him that they will organize a boycott against him for his part in Lash's election. Tony sinks into a drunken despair and the saloon is soon closed. Katie tries to reach Sally, who refuses to listen to her, and in desperation, the child alerts Harriet about Tony's woes. Harriet then tells Sally that Tony needs her and warns her that if Sally does not return, she will forget her Nob Hill pride and stand by him herself. While Katie is gone, Tony's friends return and tell him that Lash has publicly acknowledged his help and vowed to close down only the corrupt parts of the Barbary Coast. Sally also returns and celebrates with Tony, but when the reunited couple goes up to Katie's bedroom to thank her for her interference, they discover that she has run away. Tony alerts the police, who begin a search that forces Katie into a scary adventure in Chinatown. When it seems that Katie has disappeared completely, Tony realizes that she must be at the vacant lot next to Harriet's house. He goes there with Sally, and they promise the overjoyed Katie that they will be a family forever.