Spanish filmmaker David Casademunt initially conceived the original concept for the film in 2012 and began to develop the idea into a screenplay. Within the following year, the film received backing from Ventana Sur's Blood Window pitching program in Latin America and funding from
The Madrid Film School. In February 2020, Spanish production company Rodar y Rodar joined the project as the main producer. Marina Padró of Rodar y Rodar called Casademunt a "new promise of the Spanish cinema". Frequent collaborators Fran Menchón and Martí Lucas were credited as co-writers of the screenplay, and Casademunt described the feature as "a film about the demons we have inside [and] how these demons transform us into defective adults." During a press conference in October 2020, it was announced that
Netflix had acquired worldwide distribution rights to the project.
Inma Cuesta,
Roberto Álamo, and Asier Flores were cast in lead roles in February 2021. with the lagoons of
Gallocanta and
El Cañizar serving as shooting locations. ==Release==