A baby alligator is flushed into the sewers. It survives for years undetected by feasting on dead animals that were exposed to growth formulas and unwary humans who have ventured into the sewers. After years of non-stop eating, the young alligator has transformed into a monstrous 36-foot-long creature with an insatiable appetite. Now it's up to a world-weary detective and a herpetologist to stop the beast from going on a rampage.