A 20th-century aristocrat (Marcello Mastroianni) falls off a horse and becomes convinced that he is Henry IV, the emperor who ruled Rome in the 11th century. Oddly, the friends and relatives of the accident victim don't attempt to dissuade him and instead play along with his delusions. As a royal court is built around Henry, his psychiatrist (Leopoldo Trieste) attempts to figure out if the faux noble is truly insane or if he is merely milking his madness for all it is worth.