"Her name is Claire Redfield.
We caught her tresspassing in our Paris lab facility ten days ago. She apparently infiltrated the complex looking for her lost brother, Chris Redfield..."
Set just three months after Resident Evil 2 and 3,
Claire flies to Europe to search for Chris and end Umbrella's BioWeapon creations, right at the source.
Umbrella's HQ in France. Unfortunately, Claire is abducted and taken to a island in South America and finds that the virus mutations have happened on this island as well.
While Chris, hoping to find out more in Europe, somehow manages to turn up there as well.
As for the island it is known that the island is a prison, called Rockfort Prison (on Rockfort Island amazingly).