Mad Monster Party? (unrated)
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Caution: spoilers?

This came out in 1967, but I didn't see it until 2025. It's something I've wanted to see for years, but I wasn't sure how much I'd actually like it. Well, I needn't have worried; I think it's pretty damn good. It's absolutely bonkers and redonkulous, but very funny and creative. It takes time for things I wouldn't have expected it to show at all, and I found it all fairly unpredictable.

Baron Boris von Frankenstein (voiced by Boris Karloff) invents a serum that can destroy matter (in a big, nuclear-looking explosion). He invites a bunch of monsters to his castle on the Isle of Evil, to inform them of his invention, and to let them know that he's planning on retiring. Living with him are his secretary, Francesca (who kind of reminds me of Miss Bellum, from The Powerpuff Girls), his monster (who is called Fang, for some reason), and Fang's mate (voiced by Phyllis Diller, who laughs at almost everything she says, whether it appears to be a joke or not). The monsters the Baron has invited to the island include Dracula, the Mummy, the Werewolf, the Hunchback of Notre-Dame, the Invisible Man, Dr. Jekyll and Mr. Hyde, and the Creature from the Black Lagoon. He also invites his bumbling, very nearsighted nephew, a pharmacist with allergies, named Felix Flanken (whose voice actor seems to be doing an impression of Jimmy Stewart). Everyone books passage on a ship to get to the island, and I was surprised that the movie spent any time at all showing us the antics that go on there, before they get to the Isle. And... somehow, all the monsters get to the island some time before Felix does, I didn't really understand that. But it's not too important.

On the island, we also meet the baron's staff of zombie bellhops/pilots, and the head zombie/butler, Yetch (whose voice actor does an impression of Peter Lorre), who is romantically interested in Francesca, though she can't stand him. At one point, Yetch inspects the kitchen, where Chef Mafia Machiavelli is preparing the food for all the guests. Like with the ship, I was a bit surprised at how much time was spent in the kitchen. Anyway, the Baron tells Francesca that he's planning on retiring and passing on all his secrets to Felix. But she wants him to pass on his secrets to her, so she conspires with Dracula to eliminate Felix. Frankenstein's monster and his mate later get involved in the conspiracy, as well. But their plans come to naught. And eventually, the monsters turn against Francesca. So she sends an invitation to "It", a monster she had discussed earlier with the Baron, someone he didn't want to invite to the island. Meanwhile, Felix decides he doesn't want any part in the family business. And Francesca goes from hating Felix to falling madly in love with him after he slaps her. (That seemed rather problematic to me, more than funny.) So they plan to run away together.

Well, I don't want to spoil any more of the plot. I won't tell you what "It" turns out to be, when it finally arrives on the island. (At one point I got the impression it was going to "sing", but with only grunts, which I found amusing. But that didn't last long enough to really call it a song.) Most of the songs in the movie were rather weird, but not exactly bad (except maybe Diller's song). I won't say how it all ends, but it... definitely ends. Anyway, the whole movie is really weird, absolute nonsense, but it's the kind of weird nonsense that I really like. It kind of reminded me of Hotel Transylvania, in some ways. And I guess I don't know what else to tell you. But I'd definitely recommend it, if you like weird movies, and stop-motion animation, and allusions to classic horror movies.