An aspect of dying in opera, rarely observed or commented on, is Sudden Unexpected Death. There are many deaths in this melodramatic genre: most follow expected causes like murder, suicide, or old age. This book explores those deaths which occur without obvious natural causes. These are often central to the overall drama of the opera, representing denouements forming the epiphany of the story and the apotheosis for the audience. The book identifies 50 operas where such events occur, exploring the role of the dramatis personae, the circumstances of their dying, and specific themes that emerge. These include a preponderance of females, especially in the 19th century, who die mainly at the end of the operas, often in the context of tragedy. It charts the growing awareness in the medical sciences of the unconscious forces driving human behaviour, including liminal mental states and trances, which influenced these operas and continue to affect human behaviour to the present day. In addition, the changing philosophies that are intertwined with operatic narratives, in particular stemming from Kant, Hegel, Schopenhauer and Nietzsche, are important in the book's exegesis, as is the special role of Wagner's compositions. This leads to the exploration of recurrent concepts such as the Liebestod, the ewig Weibliche and redemption itself.