Samuel's Rescue - NWN Side Quest (Chapter 1)
Blacklake: Samuel's Rescue is a side quest that begins by speaking with Thurin inside of the Board Laid Bare tavern in Blacklake District. You can also start this quest by talking with Samuel inside of Meldanen's Estate when you rescue him. If you start it by talking with Samuel then all you have to do is talk with Thurin to turn it in!
For this quest you'll need to get inside of Meldanen's Estate and free Samuel from the jail cells. You can find Samuel in the southern portion of Meldanen's Estate in the jail section, as shown in my screenshot below. You can free Samuel by bashing down the cell door that leads to him or loot the key out of the chest next to the jail cell and open the door.
After freeing Samuel all that's left is to return to Thurin in the Board Laid Bare and talk with him to complete the quest.