When using the needler, the sorcerer whispers the following:
Pathetic fool! A servant of Malygos would sooner die than aid an enemy....
Aargh! Do your worst, <class>! I'll tell you NOTHING!
Aahhhh! Release me! I am of no use to you. I swear it!
Stop! I beg you, please stop. Please...
Alright! I am beaten. Your precious archmage is held in a prison, elevated and sealed. Even if you manage to reach her, Salrand herself holds the key. Your mission is folly!
At this point, you achieve the objective of Prisoner Interrogated. You still hold the Neural Needler, though, and are able to continue.
Enough! I've told you all that I know. Your continued abuse is senseless!
You aren't even asking me questions!
You have a darkness in you, <race>.
You have shown me the face of true evil, <name>.
This quest, wherein you torture someone for information, is noteworthy for its relevance to real-world events and morality. A reaction to it - on game design merits, rather than morality issues - by Richard Bartle (here, with replies found here) gained significant publication (on siteslikethese). The game design points raised seem largely to have been overshadowed by the reaction to the torture elements of the quest - the very shock Mr Bartle was thinking of when he first commented.
The whole premise is that the librarian character won't torture someone because of the morals of his group, but you (the character ... or the player) can. In fact, to complete the quest series, you have to.