The film begins with a startling news report that highlights the issue of overpopulation, not only among humans but within the animal kingdom as well. It specifically references the rabbit outbreak in Australia during the 1950s and draws parallels to a similar crisis unfolding in the American Southwest, particularly in Arizona. Here, the rabbit population has exploded, leading to widespread devastation as these creatures consume crops, damage property, and compete aggressively with livestock for limited food and water resources.
As the story transitions to Arizona, we are introduced to Cole Hillman, played by Paul Fix, who is shown riding his horse. Unfortunately, the horse steps into a rabbit hole, injuring itself, forcing Cole to take the drastic measure of shooting it and making the long journey home on foot. Determined to find a solution to the rabbit infestation, he contacts the local university in Ajo for assistance. There, he crosses paths with Dr. Elgin Clark, portrayed by Stuart Whitman, whose initial recommendation is to bring in the same individual responsible for eradicating coyotes—an idea that makes Cole hesistant. Instead, Dr. Clark proposes that Cole consult with the Bennett family, a group of scientific researchers in search of more eco-friendly methods for wildlife control.
We then meet the Bennetts—Roy (played by Chuck Hayward), Gerry, and their daughter Amanda. During this time, Roy is conducting experiments with bats to learn how to manipulate their flight for the purpose of mosquito control, all while avoiding chemical pesticides like DDT. Dr. Clark soon visits Roy, urging him to help Cole with his rabbit dilemma. As they head to Cole’s ranch, they witness ranchers battling the rabbit infestation by shooting, reflecting the desperation of their situation.
Upon reaching the ranch, Cole explains that while he is not an environmentalist, he understands that using poison to kill the rabbits could have dire consequences for his cattle, potentially making his land toxic and barren. Despite his stubbornness, Cole is tempted by Roy's suggestions to disrupt the rabbits' reproductive systems or introduce a illness that exclusively targets rabbits. Roy takes some rabbits back to the lab for testing, while Amanda develops a friendship with Cole's son, Jackie.
Meanwhile, at the university, progress stalls as their experiments yield no promising results, putting Cole's ranch and livelihood at risk. In a moment of desperation, Cole makes one last attempt with an injection on an untested rabbit, leading to an emotional conflict with Amanda, who has grown fond of the creature. Hoping to spare it from experimentation, she swaps it with one from the control group, believing it's innocent of harm.
As the narrative unfolds, Amanda's new pet comes into conflict with Jackie, leading to a sequence where he inadvertently lets the rabbit loose. Tension mounts as the university’s tests continue to fail; some rabbits are growing larger but are otherwise unaffected. Determined to find an unconventional solution, Cole resorts to burning a portion of his land to create a food-less environment for the rabbits—a risky move that pays off temporarily.
The plot thickens when unnatural animal tracks lead Cole and the Bennetts into a mine, where they confront terrifyingly large rabbits. These massive creatures swiftly transform the already critical situation into a life-and-death struggle. Just as they seem to be gaining the upper hand, a series of horrifying events unfolds, including a truck driver succumbing to a rabbit attack.
A tense search ensues, and when they do discover a large number of rabbits, chaos erupts as the group tries to contain these monstrous creatures. An explosion intended to trap them only exacerbates the situation, resulting in a terrifying rabbit attack on Cole’s ranch.
The climax is reached when they strategize using a railroad to electrocute the rabbits as they pass. Reinforcements arrive, yet they face constant pressure from the advancing horde of rabbits. As they put their plan into action amidst a flurry of gunfire, the group must overcome not just the swarm of rabbits but the ensuing panic that grips the town.
In the end, as the dust settles, Cole reflects on the ordeal, revealing that life is gradually returning to normal. With the coyotes returning to help manage the local rabbit population naturally, he extends an invitation to visit his ranch, demonstrating a hopeful outlook for the future beyond disaster. The film concludes with a message about the balance of nature and the lengths we will go to when faced with an ecological crisis.
