The Passion of Nell is based on the true story of Swedish soprano Birgit Nilsson, who was stalked for nine years by Nell Theobald, a former American model. Theobald’s obsession began during convalescence from a lion’s attack on a BMW commercial set. After being mauled, scarred, with all dreams of stardom dashed, Nell's raison d’être became attending as many shows of Birgit’s as possible, sitting front row, traveling across continents and sending dark red roses to Birgit’s dressing rooms when unable to sneak into the dressing room herself. Nell eventually committed suicide in a dark, dank Astoria, NY hotel room in 1977, and this is where the opera begins.

Set in a Bardo/in-between world, all scenes take place as Nell's life review of the significant events involving Birgit. These scenes are led by Nell's spiritual guide, Gus, and commented upon by the benevolent Chorus. In this supernatural world, we see Birgit try to save Nell before her suicide; the fateful scene of the mauling by the lion on the commercial set; the court scene where Nell is awarded only an eighth of the damages she sought; her chance for a record deal with the music producer who believes in her (when she only uses him to meet Birgit for the first time); as well as the scenes of Nell's outrageous stalking. The finale includes Nell's self-forgiveness, as well as amends with all the characters she has hurt or who have hurt her. She is finally laid to rest with an extraordinary solo by Birgit, who has forgiven her.