Little Paddy O'Day (Jane Withers) is traveling alone across the Atlantic to join her mother in America. En route she forms a kinship with the Petrovich's, a family of dancers, and a particular affinity for Tamara Petrovich (Rita Cansino). When they reach Ellis Island, immigration officers tell Paddy that her mother is ill, unable to break the real news that she has died. Paddy is held pending deportation back to Ireland. Paddy's mother was a cook in the home of Roy Ford (Pinky Tomlin), a reserved, intellectual type who lives with two stern aunts. Paddy escapes Ellis Island determined to see her mother. Alone in New York, she eventually reaches the Ford home, where she is told the truth about her mother. Knowing Paddy has no family, Dora (Jane Darwell) and the other kind servants decide to keep her there, hidden from the Ford's, until a permanent solution can be found. The aunts go away on a trip but Roy stays. The youngster endears herself to Roy and he permits her to stay. Having learned of Paddy's escape, Tamara goes looking for her at the Ford residence. They all agree Paddy should stay with her, where the police are less likely to search. Seeing Tamara makes Roy finally take an interest in something other than his collection of stuffed birds -the attraction is mutual. Tamara's family is working at her cousin Mischa's (George Givot) café, the Club Petrovich, but they do not have money for all that is necessary to make the club a success. Tamara considers returning to the old country. When Roy hears this, he becomes part owner of the club and finances the show himself. Roy's aunts return from their trip and are appalled by Roy's changed attitude and by his having fallen in love with a dancer. They find out that Tamara is harboring Paddy illegally and report them to immigration. Meanwhile, the Club Petrovich opens. Paddy and all the performers are a hit. Afterwards, Roy's aunts arrive with the authorities. They say both Tamara and Paddy will be deported, unless Paddy is adopted. The problem is easily solved, for Roy and Tamara have already been married secretly, and they wish to adopt Paddy.

Paddy O'Day is cute family entertainment. See how Rita's charm and beauty were very much evident even before the name change. She possessed these qualities always. As Tamara Petrovich she performed two Russian dances -one solo, one with other singers and dancers, in the "Which is Which" production number. This picture is also one of very few in which Rita has a significant amount of interaction with a child. Her later "image" was simply not motherly.