This sci-fi horror cult classic is based in and around a U.S. long-range radar installation in the Canadian wilderness, where soldiers and civilians alike are being struck dead by an unseen force. At first, the base commander believes these murders may have been the work of spies operating out of the woods -- a theory supported by unexplained fluctuations in power output from the base's nuclear plant. Because of the proximity of this reactor, residents of the nearby town begin to suspect the deaths are due to a radiation leak. The real answer turns out to be far more insidious. Autopsies reveal that the victims' spinal fluids have been sucked dry through holes at the base of their skulls. The bizarre murders are eventually linked to the work of psychic researcher Professor Walgate (Kynaston Reeves), whose experiments materializing human thoughts have not only been causing the power fluctuations, but have resulted in the creation of invisible brain-monsters. When the creatures attack the plant operators, a massive surge of radiation is released, revealing the creatures in all their hideous glory -- depicted by marvelous stop-motion animation -- as leaping, tentacled brains with wriggling antennae. This leads to the film's notoriously gory final act, in which the brain-things surround our heroes in a mountain cabin, descending in droves as the dwindling band of survivors hack, chop, and blast away at the beasts. After a slightly sluggish start, this intelligent and well-crafted thriller kicks out all the jams for a horrific climax, distinguished by some of the goriest effects seen in any film from the 1950s.
by Cavett Binion synopsis