Complex sentence: By 1920, Mackaill had begun making the transition from "Follies girl" to motion picture actress and that year appeared in her first film, the Wilfred Noy directed mystery "The Face at the Window".
Split into simpler sentences: By 1920, Mackaill had begun making the transition from "Follies Girl" to film actress. That same year she appeared in her first film, the Wilfred Noy-directed mystery, "The Face at the Window".