This was an early Polanski film (and yea, he was totally
set up by his 'victims' Mom for $$$)
We have an especially effective 'horror' film here,
not like the standard cartoonish Hammer fare popular
at the time - closer to the later "The Omen" and maybe
even Depp's "Ninth Gate" - although from a more
female-paranoia viewpoint.
Farrow really was a total cutie back then too :-)
Quick synopsis - couple move to a "Satan Central"
apartment building. The sweet young thing gets
preggers (husband or devilish neighbor or Satan
himself ?). She is then micro-managed/brainwashed
through the pregnancy by the Devil-loving neighbors
so she can bear the 'AntiChrist'.