People with relatives who succumb to  mental illnesses can relate to this film.  This is one extraordinary case though.  While we normally know of the usual manifestations of schizophrenia this is one curious case.  The one in control of Daniel's mind is a doctor herself and this is where the danger begins.  Daniel appears normal and treated  of his condition, or it is what it appears to be.  I would like to think this is highly probable in  the real world.  Laudable cast and  the lady doctor was totally in control.