The show opens in the "world of the dead", where Luigi Lucheni is being interrogated by a Judge as to why he has murdered the Empress Elisabeth. Lucheni claims that he did no more than what Elisabeth herself wanted, since all her life Elisabeth has been in love with Death himself – and vice versa. As his witnesses, Lucheni brings back the dead aristocracy of the bygone era and takes us to the past, where he serves as a sarcastic narrator of the events that lead to the transformation of the sweet and innocent Sisi to the revered and infamous Elisabeth, Empress of Austria and Queen of Hungary, and her decline through later years until her assassination.

The musical tells the story of Elisabeth ("Sissi"), the Empress of Austria, from her engagement and marriage in 1854 to her murder in 1898 at the hands of the Italian anarchist Luigi Lucheni, through the lens of her growing obsession with Death as her marriage and her empire crumble around her at the turn of the century.