It stars Leonor Watling alongside Pablo Derqui, Keren Hapuc, and Jaime Ordóñez.

Acting on behalf of the Archdiocese, hard-boiled nun sor Juana gets into a church in Old Madrid built over a maze of underground passages, finding that Evil has taken roots.

[7] Shooting locations in Madrid and Bizkaia included Bilbao and the Pozalagua Cave [es] in Karrantza.

[5][9][10] Carmen L. Lobo of La Razón rated the film 3 out of 5 stars, positively highlighting Watling's dedicated performance and the supernatural entities' looks, while negatively mentioning some somewhat jarring lines and mawkish ending.

[11] Philipp Engel of Cinemanía rated the film 3½ out of 5 stars, writing that "all is well on its costumbrista side", which can be encapsulated in the phrase "blacker than Pantoja's hair", pronounced by one of the characters.