The boy’s mother, Sara (Pamela Flores), is not much easier to deal with. She withdraws her maternal love after Jaime forces the boy to cut off his flowing blond locks and confounds poor Alejandro by alternating chilly reserve with erotic provocation. She also sings all of her dialogue in a soaring soprano, as if her every utterance were an aria in her own private opera. (Ms. Flores, in addition to being a fearless screen actress, is also a professional opera singer.)