Rudi Stephan's only opera retells the story of the Bible's first family just after their expulsion from Paradise. Adam searches for meaning through work and harvest, while Eve longs for intimacy and another child. Their sons are opposites: the wild, sensual Cain, and the devout Abel, who plays the perfect son. Cain whose only possible object of desire is his mother, comes to frighten her, while Abel turns to a newly revealed God who demands sacrifice. When both brothers fall for the same woman, envy drives Cain to kill his brother.

Based on Otto Borngräber's "erotic mystery" play, the opera centers on two ideas: the forbidden desire that comes from being the only four people on earth, and the birth of religion. Kajin and Chabel embody the pull between the earthly and the spiritual, leaving the family torn between God and pleasure. Stephan finished the score in 1914, but he was killed in World War I five years before its 1920 Frankfurt premiere, and this lush, rarely performed work remains one of the great operatic rediscoveries of the 20th century.