It is 1939, and the Republicans have almost lost the Spanish Civil War to the Francoists. In a remote part of Spain, the elderly Dr. Casares and the crippled Carmen run the Santa Lucía orphanage for boys, helped by Jacinto, the former orphan turned groundskeeper, and his fiancée Conchita, the cook. Casares and Carmen are Republican loyalists who hide a large cache of gold – which might explain why the orphanage has been attacked by Francoist troops, most recently by a defused bomb in the courtyard.

The orphanage is mainly populated by the children of Republicans, and the newest arrival is ten-year-old Carlos. He is assigned a bed that belonged to another boy called Santi (“The One Who Sighs”), who disappeared the day the bomb hit the orphanage. Carlos forms an unlikely friendship with the resident bully Jaime, and soon begins crossing paths with a mysterious apparition that he realizes is Santi. He eventually confronts Santi – and learns that he was accidentally murdered and thrown into the underground pool by the fascist Jacinto in his hunt for Carmen’s gold. Santi ominously predicts that “many of you will die”.

Meanwhile, convinced they have been betrayed, Casares urges everyone to leave the orphanage; the desperate Jacinto blows up the place and escapes, killing Carmen and a number of orphans in the process. He eventually returns and kills both Conchita and Casares to resume his search, but his companions desert him just before he finds the gold in Carmen’s prosthetic leg. Unfortunately for him, he is overpowered by the orphans and thrown into the pool where Santi’s body lies – and sinks due to the weight of the gold in his pockets. The orphans then walk out into the desolate countryside.