The entirety of Sheena's population worked for Umbrella in some form or another, though most of the inhabitants were unaware of the corporation's inhumane activities. In truth, the island was used to accomodate one of Umbrella's key facilities: a B.O.W. production centre where the company produced most of its Tyrant-class weapons.
On November 22nd 1998, Sheena Island became the site of a biohazardous outbreak instigated by its own commander, a ruthless Umbrella executive known as Vincent Goldman. In order to cover up a riot sparked by the island's prisoners attempting to escape being used as guinea pigs for Tyrant production, Goldman intentionally released the T-virus and infected most of the island's population, making it appear to have been an accident. Prior to the outbreak, a detective known as Ark Thompson was on the island having been assigned to investigate Umbrella's activities there. Goldman discovered the detective's presence after being informed of it by a boy called Lott Klein, a local child who acted as the commander's personal spy.
After unleashing the T-virus across the island, Goldman attempted to hunt down Ark Thompson to finish the job and then return to Umbrella headquarters to collect his earnings; and when Ark was attempting to escape Sheena Island via helicopter, Goldman tracked him and shot it down. Ark lost his memory after the fall and wandered aimlessly (though not unconsciously) through the T-virus infected city. Goldman lost consciousness when the helicopter crashed, but survived. Somehow he got back at the local Umbrella facility to call Umbrella HQ for rescue. But Umbrella, after getting the disturbing news of the outbreak, sent a squad of special clean-up forces to eliminate any survivor with knowledge of the Tyrant production instead. These Umbrella Trashsweepers (colloquially known as "Cleaners") were ordered to recover the Tyrant data and to eliminate the possible perpetrators of the outbreak.
Meanwhile, Ark Thompson began to uncover some of Sheena Island's secrets as he ventured through the city. He visited certain areas that contained classified Umbrella data. Ark managed to reach the Umbrella research facility. There, Vincent Goldman released several mass produced Tyrants to dispose of Thompson. He also found the now orphaned Lott Klein, a boy which was the son of an Umbrella employee in the island. He later recovered his memory and confronted Vincent in the research facility. During this, a prototype Tyrant (Hypnos T-Type) escaped from its container and killed Vincent in front of Ark Thompson. He survived the Tyrant onslaught and escaped the facility through a train which got Ark and Lott to a small airfield. There Ark found a helicopter and used it to escape the island with Lott & Lily (Lott's sister) Klein at his side. However, the earlier Tyrant reached the helicopter in a more mutated form. Ark managed to fire two stored missiles to the mutated Tyrant and launch it out of the plane. He then used a second stored missile to blow up the Tyrant in mid air. Ark Thompson and the Kleins escaped to safety.
Sheena Island was destroyed on November 26, when the self destruct sequence was activated.
Below is a complete list of creatures that appeared on Sheena Island.
- Zombies - Sheena Island citizens infected with the T-virus after it was released by Goldman. They could be found all over the island.
- Lickers - Zombies that underwent further mutation, transforming into quadrapedal beasts.
- Giant spiders - Arachnids exposed to the virus that grew to huge proportions. They could be found in numerous areas throughout the island.
- Zombie dogs - Umbrella guard dogs that ran wild after being infected.
- Infected crows - Carrion birds that fed on infected flesh.
- Infected cockroaches - Common pests that remained confined to darker areas, most notably the sewers.
- Infected alligator - An exotic pet of one of the island's residents, mutated by the virus and dwelling in the sewers.
- Tyrant T-103 - The primary product of the Umbrella facility on the island. Numerous T-103's were released following the viral outbreak. Oddly enough, they seemed to be much weaker than those previously witnessed in Raccoon City.
- MA-121 Hunter "α" - Reptilian B.O.W.'s and one of Umbrella's most successful products. Goldman released several Hunters to track down and eliminate Ark.
- Under Takers - Also known as "Cleaners". These were humanoid B.O.W.'s sent from Umbrella HQ following the outbreak, tasked with eliminating any survivors and collecting any materials and data vital to the corporation.
- Giant moth - An experimental insectoid B.O.W.. This experiment proved to be a failure as no other specimens were produced.
- Plant 43 - Poisonous, plant-based monsters.
- Hypnos T-Type - A one-of-a-kind experimental Tyrant created without a power limiter.