Notes: Universal International.
Dr. Matt Hastings: John Agar
Stephanie "Steve" Clayton: Mara Corday
Professor Gerald Deemer: Leo G. Carroll
Sheriff Jack Andrews: Nestor Paiva
Joe Burch: Ross Elliott
John Nolan: Edwin Rand
Townsend: Raymond Bailey
Josh: Hank Patterson
Andy: Steve Darrell
Produced: William Alland
Directed: Jack Arnold
Screenplay: Robert M. Fresco & Martin Berkeley
Story: Jack Arnold & Robert M. Fresco
Special Photography: Clifford Stone
Summary: We're treated to a slow pan of western desolation before a bipedal monstrosity in pajamas staggers and collapses. Sheriff Jack has been calling for Doctor Matt Hastings to see what he thinks of this man found dead -- Eric Jacobs, a biologist who had been working for Professor Deemer. Deemer (played by Leo G. Carroll, the poor man's Boris Karloff) identifies the body and laments the passing of his assistant and friend for 30 years. Apparently his pituitary gland went haywire and he deformed rapidly.
Deemer is experimenting with nutrients and has come up with a rapid-growth serum. He supersizes a rat, a guinea pig, and other animals. He's about to abuse a monkey when another monstrous guy attacks. In the destruction, a giant tarantula escapes before the fire breaks out. Deemer is rendered unconscious and the monster injects him before collapsing. Deemer awakens and buries the body of the monster. The monkey jumps suddenly, having escaped the fire also.
Doctor Matt objects to Deemer's "safety of prestige" and thinks something's fishy in nutrient biology experiments in the desert. Joe Burch, a reporter, snoops around the story of Jacobs and his suffocation from enlargement of tongue and organs. A woman comes to town -- "Steve," the new master's student assistant to Jacobs. Doc Hastings drives her to Deemer's and gives her the news, but she'll serve as lab assistant to Deemer now. Deemer gives them a tour of the recent damage and is asked is Paul Lund is still working for him. He nervously says no and pontificates on the growing human population and the impact on food sources in the years to come. He's using atomic radioactive isotopes as bonding agents. But there's too much instability before the "ultimate test -- on humans.... There mustn't be a mistake this time."
Steve is off for a hair appointment and the Professor is changing somehow. Steve and Doc stroll downtown and she spills all regarding a rabbit grown to maturity within six days. They drive back to Deemer's and on the way stop to appreciate the desolation and have a cigarette (which will stunt their growth?). A rock falls, so this indicates evil forces conspiring. "You can't second guess the desert," says Doc in an attempt to be enigmatic. We see giant spider legs crawling over the rocks. The thing has grown considerably. Steve invites Doc in to see the giant rabbit. There's a rat too, disturbingly large. Afterwards, the Professor is pissed at the intrusion and Steve exclaims, "Your face!"
The Sheriff reports that Andy's cattle are being eaten, the "bones just stripped clean like peeling a banana" (?). It doesn't look like the work of mountain lions, and what's that white goo? That night Andy's horses are spooked. The tarantula, grown to the size of a mountain, approaches. Andy shoots but is eaten. A truck with two men inside is also thrown. The next morning all are at the scene. The Doctor smells and even tastes the white goo. It seems like insect venom, but the quantity!
Steve calls Doc and reports that Deemer is sick. Then she screams. Doc drives there but the Professor is harmless, just grotesque. He fesses up that Jacobs and Paul impatiently injected themselves and went crazy.
The Arizona Agricultural Institute determines that the goo is arachnida venom, so we and Doc see a choppy educational film of a tarantula facing off with a rattlesnake. Tarantulas are flesh-eaters, but desert beetles are their usual prey. They inject a venom solvent to soften their meat before they start sucking. The expert says they're "just part of the world around us ... God's creatures."
Telephone lines are down. Two rubes run. Doc tells the Sheriff to alert the state police. As Steve studies in her room, the giant tarantula peeks in the window. Soon the Professor and his house are destroyed. Doc picks up Steve outside and drives off.
The Sheriff and cops make plans and two cops die. They round up all the dynamite in town, but the tarantula walks right through the explosion. Doc has the Sand Air Base drop napalm. After a couple missiles fail to stop the tarantula, they do drop napalm on the creature just yards from town. The townsfolk, who soon will have cancerous tumors popping out all over them like human Jiffybakes, cheer the environmental poisoning. A big napalm fire has the spider singed. Deep chords. No commentary.
Commentary: It's unclear how success in making gigantic humans is going to solve the food shortage problem.
The tarantula isn't particularly frightening, whether it's trying to heave rocks onto Doc and "Steve" (who wouldn't?) or roaming the Boogerville highways. The terror of the horses is probably the most disturbing feature.
The film does take an admirable stab at prophecy. The connection between animals and humans regarding Bovine Growth Hormone has been similarly unexamined, and lo, we have a nation of grossly obese meat-eaters.