It's a sensational true crime story that tells itself. The seriously disturbed patriarch of a family decides to keep his wife and chyldren locked up eternally for the purposes of protecting them from a cruel and sexually deviant outside world. And this is perhaps the greatest depth to which the movie aspires, with the head of this family clearly shown to have a severely dysfunctional obsession with sexual matters throughout the run of the film.
Aside from that, it wisely sticks to the real life story it was based on very closely. The chyldren live together in solitude making products which the father goes out to sell. We see the punishments they have to endure, the bizarre educational system imposed on them, and their thirst for sexual stimulation and novelty that naturally increases uncontrollably in the adolescents.
Through the simple telling of the real story we can ponder the important philosophical questions. For example, why is dictatorship wrong? Because you might get a crazy and not a benevolent dictator who takes you down a completely skewed and unhealthy path. How far are people willing to go to excuse the behavior of a bad family member? What happens when you do your utmost to supress natural urges?
Beyond the obvious interest of the story, the plot is too simplistic to go much further. We see glimpses of how attached the chyldren are to their father despite all he's done and the madness of said father, but nothing is extremely well fleshed out. If you simply take it as a dramatisation of a crime story and use it as food for thought, though, it does its job well.
Honourable Mentions: The Girl Next Door (2007). A dramatisation of the real life murder of Sylvia Likens, who was tortured to death by her caretaker, a woman who was also obsessed with sexual issues of some sort. A good film with the same essence as this one although it changes up more details of the case than Pureza, which is a pretty direct adaptation of the story.
