See enough movies - and more to the point, discuss enough movies - and you start to come up with shortcuts, boxes that you can file things in to help make it easier to come to grips with what they are and how to approach them. But every now and then something comes along and blindsides you by refusing to fit into any of those boxes at all, and these are the most special and rewarding of all films.

Thus it is with 1966's The War of the Gargantuas, a film that I was not prepared for at all before I saw it. You'd think it was just one of many daikaiju eiga from the mid-'60s, attempting to marry scenes of giant monsters with the styles and genres most popular internationally at that time, and while this is basically true, it doesn't even scratch the surface of a movie which absolutely beggars my ability to distinguish between something that's fun to watch because of how bad it is, and something that's fun to watch because of how legitimately great it is. Because it is, clearly, a bad movie. But it's also a movie that is terrifically entertaining and involving in a way that completely sidesteps irony.

At least, the Japanese version does: and in fairness, The War of the Gargantuas is a title better reserved for the slightly longer English dub prepared at the behest of distributor Henry G. Saperstein (the Japanese cut we might more fairly call Frankenstein's Monsters: Sanda vs. Gaira). And this version has much less ambiguity to it: it is a bad movie and then some, though a joyously bad one. I'm inclined to think that the Japanese original isn't necessarily any better, given how similar they are in plotting and even in several points of dialogue; I'm inclined to credit the tendency one has to give the benefit of the doubt to subtitled movies, there always being some level of abstraction between the viewer and the film as a result of having to read the dialogue which makes some very howlingly bad utterances seem far less ridiculous.

In fact, the two versions of the film are rather similar overall (the English dub re-edited mostly to give added prominence to the film's requisite American actor, Russ Tamblyn), but the one difference introduced in the new dialogue is a doozy, and that too sets the Japanese film far out ahead of its American brother: in Japan, The War of the Gargantuas was an outright, explicit sequel to the previous year's Frankenstein Conquers the World. In America, save for one orphaned line, replacement story writer Reuben Bercovitch did everything he could to hide that fact. I assume this had something to do with the very different set of expectations the word "Frankenstein" evokes in the Anglosphere, but whatever motivated it, it left the American film almost desperately anxious to make no real sense and feel like a morass of half-formed plotting.

Happily, that's the last I have to bother with the American movie from here on out, and now we can focus our attention solely on what I shall not continue calling Frankenstein's Monsters, because no English speaker in 47 years has ever referred to the movie that way. It still doesn't make a great deal of sense, unless you make some assumptions that the film doesn't even encourage all that strongly, but at least it's not so hysterically vague.

We show up some time after the first movie to find a ship at sea (that most reliable of daikaiju eiga staples) under attack by a barely-seen giant octopus (a revival of an idea meant to factor into the climax of Frankenstein Conquers the World). It vanishes mysteriously, but this is merely the harbinger of something even bigger and badder, a giant man-shaped green thing that destroys the boat in the flicker of an eye. The one surviving sailor (Yamamoto Ren) is delirious when he's recovered, claiming that the ship was attacked by a Frankenstein (the Japanese version prefers this term, but sometimes uses "gargantua" for no readily apparent reason), who ate the rest of the crew.

This comes to the attention of three biologists who worked the Frankenstein before, Dr. Paul Stewart (Tamblyn), Dr. Majida Yuzo (Sahara Kenji), and Akemi (Mizuno Kumi), who gets neither a title nor a family name despite being the most apparently competent of the trio, but that's what being a woman in the sciences will get you. We're clearly meant to think of these people as overlapping with the same group dynamic at the heart of Frankenstein Conquers the World, though the names are different and Mizuno is the only actor to repeat; and we're perhaps meant to assume that the juvenile Frankenstein they're seen tending to in flashbacks is the monster from the first movie, though there is no way to square that with the first film's plot, and it's also elliptically suggested that the baby monster - named Sanda - was lab-grown out of the tissues form the earlier Frankenstein. Look for airtight story logic, and you look in vain.

The plot goes a whole lot of nowhere as the scientists refuse to believe that Sanda could be capable of the evils that this other monster - Gaira he's named, out of the clear blue sky - has perpetrated, and spend a lot of time wondering what on earth could be going on. The audience, having seen from the title that there are two monsters, gets to merely wait patiently while the characters catch up, though unlike a great many daikaiju eiga that leave us with nothing but a human story for a full hour, War of the Gargantuas showcases plenty of scenes of Gaira raising hell throughout, even before he and Sanda finally meet and have their day of reckoning.

This film goes all over the map, including some of the absolute finest scenes in any Toho daikaiju eiga right next to some of the worst: Gaira's first urban rampage includes a cleverly-cut scene of him eating a woman that's legitimately disturbing for a film that wasn't intended to be taken very seriously, and then hardly any time later, he waits for an unaccountably awful American lounge singer (Kipp Hamilton) performing an uncommonly awful song (including a line about switching on a microphone in her heart) to wrap up her act, so that he can attack her. Generally speaking, the scenes with the scientists are the worst parts (worst non-musical parts, anyway), primarily because of Tamblyn: 32 years old or not, his baby face made him look ridiculous in the part of a seasoned scientist, and his ability to fake being able to understand his Japanese co-stars was nowhere near Nick Adams's (still, Tamblyn comes off better in the Japanese language version: his English dubtrack sounds like it was recorded when he was both fast asleep and stoned). But the balance of the film favors everything else, and everything else is great.

For such a daft, frivolous premise, director Honda Ishiro and cinematographer Koizumi Hajime threw themselves bodily into making it as rich-looking as I can imagine. It is easily the best-shot of the Tohoscope widescreen daikaiju eiga that I have seen, with heavy, atmospheric lighting and a huge number of impressive compositions; Stewart and Akemi's walk through a foggy forest, the cadre of teenagers they meet there, and Gaira's subsequent rampaging are all particularly well-mounted. The silliness starting to eagerly creep into the Godzilla films at this time can't be detected even a little bit in any of the staging of War of the Gargantuas: Honda's dislike of frivolous movies was more in force here than it had been in years at that point, and the business of tracking two giant potentially cannibalistic nuclear mutants is treated with immense urgency, to its absolute credit. We can thank, as always, Ifukube Akira for his pulsing march that gives so much audible shape to this urgency; I'm not going to fling around phrases like "one of his best scores", because he had a lot of great ones, but this one especially so.

We can also thank Tsuburaya Eiji for yet more great effects: the monster action in War of the Gargantuas is as good as anywhere else in the genre, with some of the best models of Tsuburaya's career and what honestly might be the single best-choreographed monster fight, as Nakajima Haruo (in the Gaira suit) and Sekida Yu (as Senda) scramble over each other furiously, brutal like most daikaiju eiga aren't because of the obviously humanoid participants, and graced with a truly brilliant climax set in a harbor, with boats being used as clubs, that self-evidently influenced Guillermo del Toro's more polished, but no more rousing Pacific Rim (del Toro has made no effort to deny this influence).

So which is it? One of the most awesome daikaiju eiga, or one of the messiest, most shabbily-written and acted daikaiju eiga? No reason at all it can't be both, and the main takeaway is this: whether it is great or greatly terrible, The War of the Gargantuas is one of the completely essential entries in its subgenre, maybe the most worthy of viewing after the irreplaceable Godzilla itself.