Desperate to save his small town, an Illinois mayor enlists two friends in a scheme to make it appear as if a Nessie-like creature inhabits the local lake in order to draw tourists and attention... and they name her "Crabby". The problem is, they are not the brightest and everything that can go wrong does as they swipe a large fish and dump it in the lake in the hopes it will cause people to think they see Crabby. The local police investigator, park rangers, and a biologist suddenly have to deal with crowds of tourists, fishermen hunting Crabby, neo-hippies out to save Crabby, a crypto-investigator looking to solve the mystery, and the news media out to get the scoop. The fate of a town hangs in the balance as general insanity competes with rational thought as they comically clash towards an ending where all are changed in some unexpected ways.