I feel that a little plenary exposition on the nature of the world of Mirabilis would not go amiss at this juncture as a bit of creative inspiration.
The year is 2098. Rapid advances in technological innovation have made the world into a cornucopia of wonders, both miraculous and horrific. For every step made toward the betterment of humanity, two more are made toward refining death into an art. Almost the whole of the known world has become a sad ruin, destroyed in titanic struggles, wracked by drought, and plagued with famine. Avery City stands as one of a handful of great metropolitan areas remaining on the North American continent. It is a seaside city, once home to a bustling commerce, now transformed into a sprawling refuge for the myriad denizens of the wastes beyond. The wealthier element of the city is forced to take ever more dramatic measures to ignore the masses of human detritus that flows into its borders seeking protection from the turmoil of the world at large. Notwithstanding, areas of beauty can still be found in Avery City, even though they serve only to throw the bleak gutters and concrete labyrinths into sharp relief. Outside certain bastions of stability, however, the occupants of Avery City's lower areas are engaged in a constant battle for survival. Existence is short, and frequently a hand-to-mouth affair. Outside of divine intervention, the only way to drag oneself out of the seething morass is under the all-encompassing aegis of S.E.E.D.
The Special Eugenics Engineering Directorate was formed under the auspices of a long past administration as a military operation charged with harnessing new-found genetic information to create a class of efficient soldiers and laborers with optimal physical and mental qualities. As the world infrastructure began to collapse, S.E.E.D. found itself shouldering more and more of the gargantuan burden of providing order to a teeming mass of chaos. Currently, S.E.E.D. is based in Avery City, where it serves as a liaison between the threadbare branches of the military, a peacekeeping force, and a very well equipped research bloc. S.E.E.D. can command a huge share of the resources available to the government, and positions in its upper echelons are are regarded with esteem by both the military and civilians. However, the research division is a closely guarded secret, protected by the highest available security measures. The tenebrous workings of the master laboratory are known to no one but the head research team, by all accounts, an even more impenetrable entity than the government itself. S.E.E.D. continues to wriggle from under the thumb of the government and the military as it subsumes both personnel and equipment. It looked as though many of its shadier operations would go undiscovered until the accident.
S.E.E.D., in keeping with its original orders, had continued human genetic research using the plethora of faceless wanderers that gravitate to Avery City. Both half informed volunteers and outright kidnap victims make up S.E.E.D.'s eugenics program of horrific physiological experiments. A serum developed by the head research team to create a breed of sterile, yet reproductively superior superhumans with infinite evolutionary potential was successfully tested on several hapless victims. These victims, known in briefing as Nephilim, perfectly displayed abilities to adapt and function within almost any array of inclement circumstances, including bullet wounds, poison, electric shock, and flame. Unfortunately, the metabolic demand produced by this augmented phenotype also made the Nephilim into vampiric entities, sustainable only by near constant infusion of DNA rich vitae. Due to an egregious shortfall in the human resources department, twelve of the strongest of these abominations escaped the secret research facility in the desert and fell upon Avery City like a plague. They formed a coven beneath the streets and their numbers grow every day. As of yet, the general public is blissfully unaware of this new threat, but S.E.E.D. has mobilized all of its considerable forces to recover, contain, or eliminate its progeny.
The rest of the story, as they say, is up to you.

