Laura and Julio by Juan Jose Millas

When their friend and neighbour Manuel is left an in coma after a car accident, Julio, a film set designer, and his wife, Laura, a masseuse in an urban spa, begin to journey down strange ways. The fact that they live in an apartment that is a mirror image of their neighbours has something to do with it, as does the fact that Julio become attracted to the land of shadows, a world that he first created to entertain a child but which then he develops for himself. Meanwhile, Laura enters into a strange correspondence of her own that lacks any recipient.