An alien invader runs rampant through the borderlands of South East Arizona, devouring anything that crosses its path and wiping out entire populations of local residents. In its relentless pursuit of prey it will eat its own kind to satisfy its hunger. This is not a monster, but the North American Bullfrog, which is a voracious carnivore with an insatiable appetite. It was introduced to the regions west of the Rocky Mountains in the early 1900's. Today, with few natural enemies the bullfrog has begun to overtake its fragile ecosystem. This is contributing to the decline of native species of wildlife in Arizona, which includes the Leopard frog and the rare Mexican Garter Snake. Efforts to contain this animal have yet to stop it. FEARSOME FROGS joins herpetologist Cecil Schwalbe on the frontlines of the struggle to protect Arizona's native wildlife and reveals the bullfrog's hunting prowess that threatens the survival of its riparian neighbors.