Satán, mon amour

Another variation on the damnation of Faust ,this waltz borrows from "mad love" -particularly the French version ("the hands of Orlac" ) starring Mel Ferrer as a pianist -and mainly from Levin's "Rosemary's baby" :the new friends whom the husband (Alda) find nice and helpful whereas the wife finds them intrusive :the "bargain " is even worse than in Polanski's movie.

The "supernatural " scenes are not convincing (nothing to match Rosemary's nightmare) ,but Jacqueline Bisset is an excellent actress (on the other hand ,Alan Alda is inexpressive, the changing in his personality does not really show) who carries the movie on her shoulders, and she gets strong support from Barbara Perkins as disturbing Roxanne and seasoned German actor Curd Jurgens.

Add a good final twist : you do not realize at once what really happened.