In Sardis County, Tennessee, Sheriff Dane Carter has learned that the word "normal" seldom applies.

When Carter and his girlfriend Dr. Staci Bridges decide to spend their day off at the lake together, they don't expect anything beyond a normal fishing trip. They certainly don't expect to discover a lake full of mutated frogs–frogs with destructive tendencies and an eerily single-minded purpose. Now Dane and Staci must solve the mystery of the frogs while trying to fight off this invading army of amphibians—an army determined to make them croak...