Young Robert "Bibi" Bonnard grows up in Ottawa, Ontario, with his parents, Jacques and Susan, and his roving rogue of a grandfather, Grandpere. Across the street is his uncle, amiable drunkard Louis, who ignores the complaints of his hard-working dressmaker wife Felice and her worries about the future of their daughter Yvonne. Louis agitates about meeting his prospective son-in-law, Alfred Grattin, a teetotaler bank clerk who wishes to marry Yvonne. Next-door neighbour and schoolmate Peggy O'Hare has a crush on Bibi, but he is as yet too young to understand. On his birthday, Bibi is taken to see the vaudeville acts at the theatre where his violinist / conductor father works. During the magic act, the Great Gaspari tries to steal a kiss from Mignonette Chappuis, the assistant he is in the process of sawing in half. She storms offstage and quits. Jacques offers her a job as a maid, which she gladly accepts. Bibi is intrigued, but a little confused about his feelings for the new addition to the household. Equally fascinated, but not at all perplexed as to why is another unexpected arrival, Uncle Desmonde, a traveling salesman and notorious. He has been summoned back to take the place of the recently deceased sales manager, though he informs his employer it is only until a replacement can be found. Uncle Desmonde starts courting Mignonette, but though she is attracted to him, she tells him she is fed up with living on the road and wants to settle down. He shows her the picture of a lovely house he expects to inherit, weakening her resistance. Meanwhile, Peggy becomes jealous of Bibi's attentions to Mignonette. Bibi has already gotten into trouble for bringing La Vie Parisienne to school. When a dirty picture is found by the principal, Mr. Frye, Peggy falsely claims she saw Bibi draw it. Bibi denies it, angering Frye. He straps Bibi on the hand three times, and tells him it will be repeated every day until he confesses. When the adult Bonnards find out, they see Frye and straighten him out, though with great difficulty. When they return in triumph, Desmonde discovers that Mignonette has quit after finding out that he lied about the house, and because she is under the impression that he has been sneaking into her bedroom and stealing kisses when she is asleep. Bibi confesses that he is the guilty party. Desmonde then realizes that Mignonette is not like all of his other women. He finds her and they become engaged. The adults explain Peggy's behavior to Bibi. To Peggy's delight, Bibi forgives her and makes her his girl. Then his voice breaks.
Richard Fleischer had previously worked with Stanley Kramer and Carl Foreman on So This is New York. They borrowed Fleischer from RKO after the director had some additional reshoots on His Kind of Woman. Fleischer brought with him his regular writer, Earl Felton. He says Kurt Kasznar wanted too much money to reprise his Broadway performance so Kramer and Fleischer cast Zero Mostel instead. However then Harry Cohn became aware of the casting and overruled it - as Mostel was politically suspect due to communist sympathies. Kasznar was cast.
