A mysterious meteor crashes in the arid landscape near Glen Canyon, Arizona, creating chaos for many. Fireman trainee Wayne Grey is caught off-guard when the meteor lands directly on his car while he is conducting fire safety drills in the desert cabin.
In the wake of the crash, Ira Kane, a biology professor at Glen Canyon Community College, navigates the challenges of teaching students who fail to grasp the simplest of concepts, declaring Deke and Danny as the least knowledgeable in his class. However, the following day, Ira and his geology colleague, Harry Block, head out to investigate the incident after receiving urgent news about the meteor landing. They’re joined by Nadine, a determined student seeking extra credit, who aspires to become Miss Arizona while getting into nursing school.
As they arrive at the crash site, Wayne reveals that the meteor has submerged into a network of underground tunnels, with the local sheriff, Officer Drake, noting its remarkable depth of 80 feet. The duo collects a sample of the glowing blue liquid, discovering it contains alien microorganisms that evolve at an astonishing pace, multiplying into multi-celled organisms within mere hours.
Ira and Harry’s excitement escalates as they witness the extraordinary quick evolution that would typically require millions of years on Earth. Eager to maintain control of their discovery, they plan to keep their work away from government oversight. Meanwhile, Wayne struggles during his fire training, failing a critical test and working a second job as a pool manager, where he stumbles upon strange creatures lurking in the water supply room.
As military forces led by General Russell Woodman and Colonel Flemming arrive, Ira and Harry are determined to stake their claim to the research. They face off in court against Dr. Allison Reed, whose nonchalance about their scientific breakthroughs infuriates them. Amidst unexpected revelations about Ira's controversial past involving army experiments, alien life forms start breaching the surface.
The professors and Wayne make startling discoveries of bizarre creatures that indicate the aliens' desperate attempts to adapt to Earth. As they venture deeper into a valley filled with monstrous entities struggling to breathe oxygen, chaos ensues when one newly-emerged creature causes panic at a mall. Wayne ingeniously uses the mall’s sound system to lure the alien in order to neutralize the threat.
However, with the escalating intensity of the situation, it becomes a race against time as officials plot to contain the alien outbreak. They find themselves in a frantic fight against alien primates and the impending napalm strike orchestrated by Woodman, who is intent on eradicating the problem.
With ingenious teamwork, the group employs selenium, discovered to be poisonous to the nitrogen-based aliens, and concocts a plan to use Head & Shoulders shampoo as a weapon against the growing alien menace. They overcome obstacles, with the battle culminating in a daring maneuver to eliminate the rapidly evolving alien mass threatening to engulf the entire nation.
In a moment of triumph, after successfully bringing down the colossal organism, a grateful Governor Lewis hails Ira, Harry, Wayne, and Allison as heroes. The story wraps up with a light note, showcasing Ira and Allison sharing a moment of romance amidst a chaotic backdrop, while Wayne celebrates his newfound recognition as a firefighter. The credits roll with a humorous commercial featuring the trio, emphasizing the bizarre yet thrilling escapade they embarked upon.
