A space shuttle crashes containing a lethal prototype organism designed to survive in any environment. The only people who can stop the creature are the Secretary of Defense agent and the female scientist who created it.
| Actor | Role |
|---|---|
 Patrick MuldoonMike Connors | Mike Connors |
 Theresa RussellDr. Nancy Burnham | Dr. Nancy Burnham |
 Curtis ArmstrongKeach | Keach |
 Tamara DaviesSid Bream | Sid Bream |
 Lydie DenierDiane Cafferty | Diane Cafferty |
 John BeckSimpkins | Simpkins |
| JJoe AvalonSgt. Tulley | Sgt. Tulley |
 Daniel QuinnAlan Stanton | Alan Stanton |
 James CromwellMP 1 | MP 1 |
 Joe SabatinoMP 2 | MP 2 |
| BBilly KeaneSteve Elkins | Steve Elkins |
 Rod McCaryDr. Shoup | Dr. Shoup |
 Lorissa McComasChelsea | Chelsea |
| WWilliam LangloisGeneral Cartwright | General Cartwright |
 Andy MilderChambers (Head of NASA) | Chambers (Head of NASA) |
 Rene RiveraGonzales | Gonzales |
 Tim ThomersonSheriff Morgan | Sheriff Morgan |
| EEric James VirgetsDeputy Ferguson | Deputy Ferguson |
| SSteve PurnickMr. Norton | Mr. Norton |
 Adam LiebermanCrewman Terrance | Crewman Terrance |
| DDwayne ShattuckCrewman Miller | Crewman Miller |
 Redmond GleesonLocal Man | Local Man |
 GiGi ErnetaGirl by Pool (uncredited) | Girl by Pool (uncredited) |
 Todd KimseyCrewman Mitchell | Crewman Mitchell |