On a winter's day in 1916, Charlie Chaplin is spotted in over 800 places simultaneously - an extraordinary mass delusion in an America desperate for distraction from the oncoming war. From there, Sunnyside follows the overlapping fortunes of Leland Wheeler, son of the world's last (and worst) Wild West star, as he heads to the battlefields of France; snobbish Hugo Black, drafted to fight under the British General Ironside in Siberia in the Allies' doomed attack on the Bolsheviks; and Chaplin himself, facing a tightening net of complications - studio moguls, questions about his patriotism, his wayward heart, and most menacing of all, his mother - that stand in the way of his finally making a movie to match his talents.