When flesh-eating piranhas are accidently released into a summer resort's rivers, the guests become their next meal.
When the experienced guide Vic accompanies the city boy Alan and his three friends on their first wilderness experience, he not only hopes to teach the four boys lessons about the wilderness, but about themselves. Vic pushes them to the limit. Soon after alienating the boys, Vic finds himself in desperate need of help and must rely on his students in order to survive.
At a party, someone goes insane and murders three women. Falsely accused of the brutal killings, Jerry is on the run. More bizarre homicides continue with alarming frequency all over town. Trying to clear his name, Jerry discovers the shocking truth...people are losing their hair and turning into violent psychopaths and the connection may be some LSD all the murderers took a decade before.
