Twelve years ago two incidents occurred which bore no similarity until now. After returning from their Florida vacation, the Kendal family decided their pet baby alligator was too much of a nuisance and flushed him down the toilet. At the same time, Slade Laboratories was conducting secret hormonal experiments with dogs and the dead dogs were disposed of in the city sewer. The baby alligator fed on the dead dogs...and after twelve years its body chemistry took on grotesque mutations. When several brutal murders are discovered, David Madison is put on the case to find the so-called Jack-the-Ripper killer. But this is no human psychopath - it is a ravaging animal-turned-monster bent on destroying everything in its wake.