In the intense Madrid summer, undercover cop Erica Sánchez struggles to be herself. The roles that she is expected to play -devout Muslim, anti-system rebel, conventional fiancée- are everything that she is not. She longs for the peaceful mountains of Asturias, where her boyfriend has been sent on an assignment. So when the city becomes unsafe, it is there that Erica flees to join him. Only the old mountains hold an unimaginable secret.