They used to say "don't trust anyone over 30," but there's no one over 30 left to distrust in this loosely plotted satirical comedy directed by Roger Corman. During the opening ceremonies for a chemical and biological weapons facility in Alaska, an experimental gas is accidentally released which has an unusual effect -- it rapidly advances the aging process of those over 25, while those under 25 are left untouched. Soon, the world's elders are dead, with the planet left to the youth. Wisecracking hippy Coel (Robert Corff) and his girlfriend, Cilla (Elaine Giftos), discover that rookie cops and conservative frat rats have taken over their hometown of Dallas, TX, so they hit the road in his vintage Ford Edsel in search of a friendly commune in New Mexico. Along the way, they pair up with music-obsessed Marissa and her radical boyfriend, Carlos (Ben Vereen), and as they look for their new home, they encounter Hell's Angels-turned-country club members, a neo-fascist football team, a pack of painfully shy would-be sexual predators, rock star and self-proclaimed "godhead" A.M. Radio (Country Joe McDonald), and Edgar Allen Poe (Bruce Karcher), who roams the highways on his motorcycle. Gas-S-S-S! (aka Gas-s-s-s...or, It May Become Necessary to Destroy the World in Order to Save It) proved to be the last of Roger Corman's many projects for American International Pictures; according to Corman, AIP subjected the film to severe prerelease cutting without his consent, and the interference was one of the factors that inspired him to start his own company, New World Pictures. The film also provided early supporting roles for Bud Cort and Talia Shire, the latter billed as Tally Coppola; psychedelic rock band Country Joe & the Fish appear in a concert sequence and provide the film's musical score.