In a remote and idyllic forest, a group of six young men and women are growing an illegal field of marijuana. The forest, under the jurisdiction of a government office, is so vast that surveillance is accomplished only four times a year by the agency field man, Cole. Two agents armed with rifles come across one of the young women farming the marijuana. She tries to flee and they shoot and kill her. Alerted by the noise, and fearful of their own discovery, the other farmers attack and kill the agent.
Meanwhile, in Washington, the head of the agency authorizes the forest area to be sprayed by Dromax, a defoliant not fully tested but feared to have bizarre side effects. A drunken pilot dusts the forest area where the marijuana is being grown and the farmers are caught in the spray and covered with dust. The results are horrendous. The young people are turned into bloodthirsty ghouls bent on cannibalism.
Cole is touring the forest with his wife and brother. Also in the forest is a family of four - one a retarded youth - plus a hermit, a farmer, and others. All are threatened by the crazed marijuana farmers - and the result is murder and mayhem!