People in movies love puppets. There's this pre-code Frank Capra movie called The Miracle Woman, in which Barbara Stanwyck is absolutely enraptured by the sight of a guy making a puppet dance. He does this for hours in her bedroom, which is why it was important that someone invent television.
Anyway, this is another movie where a ventriloquist's dummy causes people to go into raptures of delight. It turns Anthony Hopkins from an unsuccessful magician to a sensation. And that's hard to understand, because the dummy is creepy as all get-out. Plus, it looks kind of like Hopkins, except that it has an even bigger head. The hardest thing to accept in the movie is that everyone loves the puppet, even though it's incredibly creepy. As a result, Ann-Margret comes off as crazy, because she keeps giggling and shouting about the wonders of Anthony Hopkins and his simplistic magic tricks and his evil puppet.
Note that I refer to the "evil puppet". This isn't a movie where the puppet has a life of its own, so we're not talking about Child's Play here. Unfortunately, this is a movie where Anthony Hopkins can't control what he has the puppet say or do. So he has arguments with it when he's alone in the room and ends up getting bullied by it, which represents him not being able to control that side of his personality. It's pretty silly, is what it is.
The movie is exceedingly artsy, sinc Richard Attenborough was only making it so he could get the money to make Gandhi, and it features Anthony Hopkins being an unhinged angry jerk. He gets hosed down with a lot of Angry Sweat in this movie. And then there's also the creepy puppet, which is enough for most people even without the story or acting.
Penn & Teller fans may be interested to know that there's a big scene in which the key card is the three of clubs.
Bonus line: I like the time when Burgess Meredith (as the slimy agent) says "My God, the IQs alone must go to a hundred!"