Evolution (film) - Plot

Plot

A meteor crashes into the desert near Glen Canyon, Arizona. College professor Ira Kane (David Duchovny) and his colleague, geology professor Harry Block (Orlando Jones), investigate. They meet Wayne Grey (Seann William Scott), a fireman trainee whose car was damaged in the strike and discover the meteor deep in an underground tunnel network, taking a sample of strange blue liquid that oozes from it. Ira discovers that it harbors extraterrestrial single-celled nitrogen-based organisms multiplying exponentially, condensing millions of years of evolution into minutes. The next day, they take the science class to survey the meteor site and find it already surrounded by evolved oxygen-converting fungi and alien flatworms, later discovering the cells and organisms reproduce rapidly through mitosis.

Soon Ira and Harry find the site sealed off by the Army, who have set up a base. They take General Russell Woodman (Ted Levine) and clumsy Dr Allison Reed (Julianne Moore), who dismiss the duo, to court for the right to be part of the research. However they are barred from the site when Woodman reveals that Ira was discharged from the army for creating an anthrax vaccine that led to terrible physical disorders. When Woodman confiscates their research, Ira and Harry infiltrate the base underground to get another sample and find an alien rainforest teeming with life. Reed apprehends them but they are interrupted when an alien insect gets inside Harry's body, which has to be removed rectally by a doctor.

Wayne recovered the dead body of an amphibian alien which killed a country club owner and another creature appears in a woman's house but also dies. Ira and Harry theorize the aliens are escaping the caves to adapt to the oxygen atmosphere. The trio find a valley strewn with dead and dying dragon-like creatures, one of which gives birth before it dies. The young creature, adapted to the oxygen atmosphere, flies away to a mall. The trio procure shotguns at a store and chase it, killing it by drawing it in through Wayne's singing on the mall's sound system and shooting it. They then celebrate their heroics in the car back to the research lab.

The Governor of Arizona (Dan Aykroyd) demands to know what is happening. Allison explains that in two months the aliens would engulf the entire United States, so Woodman explains his plan to evacuate everyone within five miles of the infected area and bomb the aliens with napalm. The aliens, now evolved into primate-like creatures, climb up from the caves below and attack them, but are fought off.

Fed up with working with Woodman, Allison gets Ira's stolen research back to him, joining his gang at the college as the town is evacuated. There, Harry accidentally tosses a lit match into a petri dish of the blue alien liquid, causing a mass to rapidly grow from it: they realize that heat triggers the rapid evolution which would mean that the napalm would have the opposite effect. Looking at the position of nitrogen on the periodic table, Ira figures that selenium might be poisonous to the aliens, since they are nitrogen-based, as arsenic is poisonous to Earth's life. Allison calls Woodman to prevent the napalm strike but Woodman ignores her. Ira's students Deke and Danny (Ethan Suplee and Michael Ray Bower) recall that selenium sulfide is the active ingredient in Head & Shoulders shampoo.

The team empties stores of the shampoo and steal a firetruck. Everyone pours the shampoo into the truck's water tanks, while Allison and Ira bond. The napalm strike begins early however, triggering a gargantuan amoeba-like organism to bulge out from the caves and kill the caves' other aliens; it then begins to divide to start the process over. The team decides to push on despite this set back and drive the firetruck under the organism, where they find a rectal hole. Harry climbs the firetruck's ladder and inserts the firehose to pump in the shampoo, causing the organism to explode. Governor Lewis declares Ira, Harry, Wayne and Allison heroes, making Wayne a firefighter while Ira and Allison skip the festivities for romance in the fire truck. Harry, Ira and Wayne then appear in a commercial for Head & Shoulders.