Once upon a Time (1944)

Alexander Hall's charming modern fairy-tale stars Cary Grant as Jerry Flynn, a Broadway producer in need of money who sees his financial salvation in young Arthur Thompson's caterpillar that dances to the tune of Yes Sir, That's My Baby. Exploiting the kid, Flynn makes his money but as his act disappears as a butterfly, he finds something more valuable in the shape of love interest Jeannie, Arthur's older sister.