In the late 19th and early 20th centuries, child vaudevillian Buster Keaton (Larry White) stays in boarding houses, rides in train boxcars, and performs with his mother and father in a knock-about (physical comedy) act called The Three Keatons. As a young man Keaton (Donald O’Connor) travels on his own to Hollywood and tricks his way onto the grounds of silent-film studio Famous Studio as a workman carrying a board, as in one of his trademark comic bits.