Toxic waste dumping in a small Idaho town turns a young boy into horrible mutant monster. The town's police chief and a government scientist team up to stop the monster, which is quickly killing off the town's citizenry.
| Actor | Role |
|---|---|
 Martin LandauGarson Jones | Garson Jones |
 Marianne GordonLaurie | Laurie |
 Bill OscoDetective Mortimer Lutz | Detective Mortimer Lutz |
 José FerrerMayor Gordon Lane | Mayor Gordon Lane |
 Dorothy MaloneMarge Smith | Marge Smith |
 Ruth BuzziVirginia Lane | Virginia Lane |
| MMurray LangstonArn | Arn |
 Kinky FriedmanWillis | Willis |
| JJohnny DarkJohn | John |
 Kent PerkinsOfficer Dudley | Officer Dudley |
| RRoxanne CybelleSuzie | Suzie |
 Jerry MarenMonster | Monster |
 Richard MarcusJoe the Lab Assistant | Joe the Lab Assistant |
 Robin StilleGirl at Drive-In Theater (uncredited) | Girl at Drive-In Theater (uncredited) |
| VVern StiermanNarrator (voice) (uncredited) | Narrator (voice) (uncredited) |