Killing Formosa - NWN Side Quest (Chapter 1)
Blacklake: Killing Formosa is a side quest that begins by speaking with Meldanen inside of Meldanen's Estate. You will have to hurt Meldanen enough until he gets down to "Badly Injured" and surrenders to start this side quest. During your dialogue with Meldanen offer to get rid of Formosa for some gold and you'll start this quest.
For this quest you have to eliminate Formosa in the Blacklake District. If you don't already know where she is, you can find Formosa in the southeastern portion of the Blacklake. She is the woman standing on the circular platform essentially encouraging a mob. Use my screenshot below if you need help locating her.
Once you've defeated Formosa return to Meldanen to complete this quest.