An Irish washerwoman's daughter falls in love with one of America's most eligible bachelors, much to the dismay of the girl's parents -- and the young doctor's newly acquired fiancée! Events come to a head at the charity masked ball, which the two girls happen to attend in very similar costumes, thanks to the largesse of Molly's benevolent "fairy godfather"; Molly is mistaken for her rival, much to the indignation both of her working-class would-be suitor and the doctor's would-be bride.