A team of Navy scientists is sent to a pacific atoll once used for atomic testing, where they hope to ascertain what happened to the now-vanished team that previously occupied the island. Once there the team is lowly whittled down by mysterious creatures that call to them in the night with the voices of those who have gone missing, and it soon discovered that the island is home to huge mutant crabs. These monstrous arthropods absorb the characteristics of what they devour, so they have taken on the intelligence of the humans they've eaten, as well as hideous quasi-human hybrid features, and they have rendered communication with the outside world impossible, so the Navy scientific team's hope of rescue is nil. And as if all of that were not dire enough, the island is geologically unstable, gradually eroding into the sea, which does not bother the crab monsters at all because they can simply survive beneath the waves in undersea caverns while they prepare for the impending end of their reproductive cycle — meaning more of them are on the way, many more — and work on their plan to eventually destroy the world.
A flick that I saw endlessly referenced in books on sci-fi/horror movies and issues of FAMOUS MONSTERS OF FILMLAND, ATTACK OF THE CRAB MONSTERS is emblematic of 1950's movies milking the relatively-new mystery of atomic energy and what could happen as a result of its utilization. It bears a lurid title and some seriously ridiculous-looking monsters, so one can be forgiven for pre-judging it as just another of its era's disposable would-be shockers, but it's a much better effort than it has any right to be. Gorier than expected for a film of its vintage — it features a Navy team-member getting his head gnawed off, while another loses a hand — and showcasing some truly Lovecraftian ideas that work despite its cheesiness and goofy-looking-at-first-glance title threat, ATTACK OF THE CRAB MONSTERS is one of those films whose scares take a little while to sink in, becoming quite horrible when one has time to really think them through. It's also a hell of a lot of fun in that Saturday matinee popcorn-muncher way that was once familiar from films of this ilk having regular airings on local TV horror/sci-fi movie shows, so it's an ideal creeper with which to indoctrinate the little ones. In fact, the more that I revisit these old horror/sci-fi cross-pollinations, the more I realize that a good number of their stories would have been right at home on classic-era DOCTOR WHO, which is only a good thing.
Poster from the original theatrical release.