Delphine Marchetti, 20, comes from a once-respectable middle-class family on the West Coast. As a child, she witnessed her mother die tragically during her second pregnancy because of her father’s affair with the family’s music teacher, Odette Kessler. Years later, through a high-end domestic staffing agency, Delphine enters the Halloway family estate under the alias “Della” to work as a maid—serving the lady of the house, Odette, the very woman who destroyed her family.