The film was directed by Stuart Orme and stars Donald Sutherland, Eric Thal, Keith David, Julie Warner and Andrew Robinson.

The team manages to capture the alien and, after a chase during which multiple infected town citizens attempt to stop them, they return to their plane.

The slugs soon spread steadily from the infected town and during a staff meeting where the team discusses the situation, Sam notices that Jarvis has stopped chain-smoking.

Along with communicating telepathically, the aliens have the ability to correct any ailment affecting the host (such as Jarvis's chain-smoking and Greenberg vision issues).

The President arrives and is saved from his now-infected security detail by a tactical team of uninfected agents working for Andrew and Holland.

Back in the office, Andrew, Mary, Holland, and Dr. Graves (the lead medical researcher for the team) interrogate the infected Sam.

Andrew recommends to the President that the US military be sent in to clear out the aliens, which have now infected the entire area, as well as members of local law enforcement and of the Iowa National Guard.

The third chimpanzee then types a message to Sam on a computer asking him if he remembers it, thus confirming that all of the aliens share the collective knowledge of the entire group.

Sam manages to find Mary and, after nearly killing her to remove the alien from her back, she informs him that they need to retrieve a child that had been kept in isolation from the infected townspeople.

As Sam and Mary are retrieving the child, Alex comes under heavy fire from infected soldiers and townspeople, falling into the pool where the aliens reproduce.

While Sam and Mary retreat to the extraction point with the child, the now-infected Alex confronts them after tracking his partner through each others' equipped location beacons.

After a brutal fight, Alex manages to briefly break the mental hold the alien has over him through sheer will and tells Sam to leave him.

[4] Further rewrites were motivated by cost saving measures such as the replacement of the novel's futuristic setting with a contemporary one, and attempts to distance the film from the various derivative works such as adaptations of The Body Snatchers.