Sheena Island was a small European island that Umbrella had managed to outright buy due to the company's abundant funds and extensive influence. Due to this, Sheena was essentially the model city of Umbrella, with almost every man and woman being an employee of Umbrella in some shape or form. The island itself was of dire importance to Umbrella, as the mass-production program for the Tyrant (T-103) model was initiated here at an aptly named Tyrant Plant at the top of the island's mountains. The method for mass-production was also presumably discovered here, the use of a chemical known as Beta Hetero Nonserotonin.
The entire island was run under the command of Vincent Goldman, a ruthless and cold employee of Umbrella who had garnered nothing but disdain from the civilians on the island. At one point, Goldman hunted down and murdered a series of escaped "guinea pigs" and attempted to cover up the truth of the incident as a mass suicide. However, a group of detractors learned of the true nature of the incident and subsequently began to conduct an investigation into Goldman, gathering evidence against him to be presented to the routine Umbrella management inspection team set to arrive very shortly. In late October 1998 in an act of sheer insanity, Goldman unleashed the T-virus upon his own island, effectively creating a second Raccoon City disaster.
Thanks to the efforts of Ark Thompson, the Tyrant Plant was destroyed following the detonation of it's self-destruct sequence.