Twin sisters Julia and Sara (each played by Belén Rueda) both suffer from a degenerative eye disease that robs them of their sight; Sara lost her vision completely, and it’s only a matter of time before Julia’s sight follows. The film begins with the death of the blind Sara, apparently being menaced by someone in her home, then hanging herself. Details surrounding Sara’s death don’t add up for Julia, however; why would Sara kill herself? She was scheduled to have an operation to restore her sight, and she just met someone. Julia and her husband Isaac (Lluís Homar) begin to investigate, but time...