The oncologist wife of a prominent child psychologist suspects her husband has an unhealthy scientific obsession with their child, unaware of what - or who - is really going on inside his head.
 
To be honest, I'm "Split" on this one...Ba-Dum Dum Ching.
 
FUN FACT:  In 2012, Peet Gelderblom, a devoted fan of Brian De Palma, did a fan re-cut of this film after becoming aware of De Palma's regret of changing the first half of the film during post-production. The film was originally supposed to begin with Jenny's subplot of the film and the Carter Nix/Cain's subplot was supposed to emerge later in the story. After acquiring a copy of De Palma's screenplay, Gelderblom re-ordered the scenes as originally intended and it was released on the website Indiewire on January 31st, 2012 with positive feedback. Even Brian De Palma himself was very pleased with the results. So much so that when the film was going to be released on Blu-ray by Shout! Factory in 2016, De Palma was able to convince Shout! to hold off on their initial release so the Re-Cut could be included on the Blu-ray. What was just a fan re-cut of the film has now officially become De Palma's Director's Cut. Gelderblom expressed on his website how extremely happy he was.