A thematic sequel to "Suspiria" (1977), the film is the second part of Argento's Three Mothers trilogy, though it is the first in the trilogy to explore the idea of the Three Mothers. The long-delayed concluding entry, "The Mother of Tears", was released in 2007. All three films are partially derived from the Thomas de Quincey work "Suspiria de Profundis" (1845), a collection of prose poetry in which he proposes the concept of three "Ladies of Sorrow" (Mater Lachrymarum, Mater Suspiriorum, and Mater Tenebrarum), concurrent with the three Fates and Graces in Greek mythology.