Filla was a member of the female Martense coven. She, along with Imogen and Symbaline were sent to Lorwich by the coven's queen to vanquish the evil there.
The three split up, with Filla exploring the local trainyard, while Symbaline and Imogen each explored the church and the lorwich mine, respectively.
None of three sisters returned, which prompted Celeste to head to Lorwich in order to find out what happened to them, and to rescue them if they were still alive.