Heather O'Rourke and Zelda Rubinstein are the only players from the first two films to cross over into the light of Poltergeist III.  Here, O'Rourke's character, Carol Anne, seemingly dumped by her parents for reasons unknown, is taken care of by her Aunt Patricia (Nancy Allen), Uncle Bruce (Tom Skerritt), and teenage step-cousin, Donna (Lara Flynn Boyle), living in a high-rise building in Chicago.  Carol Anne has been enrolled in a school for gifted but troubled kids, as her therapist, Dr. Seaton (Richard Fire), thinks that the young girl has the ability to hypnotize people into believing her delusions about seeing ghosts.  Seaton forces Carol Anne to speak about her experiences, which brings to light her involvement with the dreaded Reverend Kane (Nate Davis), and this talk has caused the late Reverend to cross over into trying to get in contact with the girl again.  For some reason, the entire building is chock full of mirrors at every turn, which is convenient to the haunting that emerges, as most of its haunting involved scaring the bejeesus out of the family and their cohorts through reflections in whatever mirrors they happen to be looking at.