The world has gone through many changes. Science has done most of that for us. Science has also been the one to doom us all. Created a massive bio-hazard that turned most of an entire city's population into flesh eating monsters. But alas, it has happened again. Now New York City has fallen into this horrible plague. But, these monsters are the least of the population's worries. While people continue to be killed by these creatures, it would seem some were killed by another means. While most of the victims had a trace of the T-Virus within their wounds, these newly killed people had no such trace. There were slash marks around their body, but no sign of the T-Virus. Any possability of a Hunter was completely thrown out. So, what could this new creature exactly be? If it is not infected, that what exactly is it? We have yet to discover what this creature truly is, or it's true purpose of killing other living beings.
Yes, massively short, but that's what prologues are all about: Setting you up.