The Tortured Noble is a quest received in the dungeon of the Arl of Denerim's Estate.
Walkthrough
Oswyn can be found in the torture room in the basement of the Arl of Denerim's estate. There will be five Torturers in the room with him, one of which is a Boss rank. After defeating them, free Oswyn from the rack and speak to him.
The Warden can then receive a reward by speaking to Bann Sighard, located in the Gnawed Noble Tavern. Speaking to Sighard brings this quest to an end.
Rewards
- A vote for The Warden in the Landsmeet.
- The Bann will talk to Bann Reginalda of the White River Bannorn as well.
- 40
(50 with a second persuasion check) - 250 experience points, but only if you accept a reward of at least 40 .
If you decline the opportunity to request a reward in gold sovereigns, you will forfeit both coin and experience points as rewards. The Bann will still support you at the Landsmeet, though. Additionally, if you respond with the "I need no thanks for simple compassion" option, 
Wynne approves (+1), if she is in the party.