Bavarian girl Elisabeth (Romy Schneider), who's known as "Sissi," is a naive teenager raised by Duke Max (Gustav Knuth) and Duchess Ludovika (Magda Schneider). Sissi's sister, Nene (Uta Franz), is due to marry Austrian Emperor Franz Joseph (Karlheinz Böhm). On the way to the wedding, however, the emperor and Sissi accidentally meet, and the two fall for each other. They cancel the arranged marriage and decide to wed, even if that means dealing with Franz Joseph's infuriated mother.