It stars Marisa Paredes, Eduardo Noriega, Federico Luppi, Irene Visedo, Fernando Tielve, and Íñigo Garcés.

Casares, a doctor, and his friend's wife, Carmen, operate a small orphanage in a remote part of Spain during the Spanish Civil War.

Casares and Carmen take in Carlos and soon he strikes up a friendship with Jaime, the orphanage bully, as well as Galvez and Owl.

Carlos soon begins having visions of a mysterious entity and hears stories about a child named Santi who went missing on the day the bomb was dropped in the courtyard.

Jacinto knows of the gold hidden at the orphanage and uses his affair with Carmen as an opportunity to take her keys and search for the treasure.

He sneaks out and encounters the pale figure of a young boy with a bleeding wound on his head, which causes him to run back into the building.

Fearing he will soon be tortured into revealing the gold's location at the orphanage, he convinces Carmen that they must evacuate the children immediately.

Jacinto overhears the conversation and confronts Carmen, demanding the stash of gold and crassly bringing up their affair in front of Casares.

In anger, Jacinto shoved Santi against a stone wall, giving him a severe head injury and sending him into shock.

Conchita attempts to walk to the nearest town for help when she encounters Jacinto and two associates driving back to the orphanage to claim the gold.

Weighed down by the gold he was carrying, Jacinto struggles to resurface but Santi's ghost appears and drags him to his death.

[5] According to del Toro, and as drawn in his notebooks, there were many iterations of the story, some of which included antagonists who were a "doddering ... old man with a needle," a "desiccated" ghost with black eyes as a caretaker (instead of the living Jacinto who terrorizes the orphans), and "beings who are red from head to foot.

[7] One scene showed jars of a liqueur the doctor owned, each containing spiced rum called “Limbo water”, preserving a fetus that died from spina bifida.

"[11] DDT Studios in Barcelona created the final version of the crying ghost (victim and avenger) Santi, with his temple that resembled cracked, aged porcelain.

The website's critical consensus reads, "Creepily atmospheric and haunting, The Devil's Backbone is both a potent ghost story and an intelligent political allegory.