In 1998, the horrors of what biological warfare were finally revealed in what most now refer to as 'THE RACCOON CITY INCIDENT', an event stemming from the major pharmaceutical corporation Umbrella. Umbrella covertly doubled as an organization that formed Biological Organic Weapons, working outside of the public eye but inside the United States government. The Umbrella corporation became virtually untouchable until these occurrences -- both with the research facilities in the Arklay Mountains, along with the irreversible losses of the Raccoon City inhabitants -- tied them to what was potentially a life altering menace that was all but "eradicated" in the fall of the corporate giant's death in 2004.
The events that led up to the bombing of the city in order to contain and maintain world safety from the infection spreading were shrouded in uncertainty and carefully constructed lies. The truth? That was only the start. Corporations worked along side Umbrella while creating the B.O.W.s, along with synthesizing the viruses that stemmed from the original Progenitor Virus. Such actions gave the subtle clues that the influences of Umbrella was not just contained within the company itself, but followed other pharmaceutical corporations that ran shady operations to form these viral weapons. The other two known companies that contained the viruses and the manpower to carry on Umbrella's work were Wilpharma and Tricell. However, only one had the founder of Umbrella, and current global fugitive's fingerprints deeply embedded one of the corporation's that would carry on the work from the foundations set by Ozwell E. Spencer.
The rise of Tricell's shadowed operations was less in the public eye then the failed run of Umbrella, which was headed by Albert Wesker. The corporation followed after Spencer's footsteps but took things up one level. The experiments stemming from the Spain incident following the disappearance of the United States President's daughter, Ashley Graham, shed light on a parasitic organism referred as Las Plagas; a vital part of Wesker's next goal to make a controllable and dominant society of "super soldiers"--perfecting what Ozwell Spencer failed to translate from theory to reality. Tricell's success wouldn't have full effect until Albert Wesker squared off with Chris Redfield (of the BSAA) and Jill Valentine (of the former Raccoon City group S.T.A.R.S)--following the "assassination" and recovery of Umbrella's founder Ozwell Spencer. The final stage of the Uroboros project created from the stolen samples of Las Plagas from the kidnapping incident in 2004; using Jill Valentine as the first successful human trial.
Tricell managed to keep its extracurricular activities under the radar from the now ever judging global public to any corporations that could be associated with Ozwell Spencer's discoveries. The move from Europe to South America was a preemptive strike in ensuring that the Uroboros project would have the foreseeable problems worked out before Wesker's main goal could be fully realized by the world. The country of South America had become one of the final battle grounds in maintaining sanity, and more importantly, individuality in the world.
Tainted Blood is set in between the fourth and fifth installments of the Resident Evil series.