NOTE TO Franz: All of this information here in the 'Main Quest' lore pages is not known by the NPCs unless they are specifically mentioned to know about a piece of information.
Travelling to @Stillwater and talking to the inhabitants there, you find that @Myrth may know where @Qintarra is.
Talking with @Myrth, two outcomes are possible : either you're an elf and he'll make fun of you, or you're not and he agrees to tell you where @Qintarra is, if you return the pelt of the @Stillwater Giant to him. He tells you to talk with @Stanley Xavier Hippington. He will tell you tales of the @Stillwater Giant and its unique ability to transform itself into a blue rabbit. He will give you a trap and scent to attract it and tells you to search the @Stillwater Giant's Lair behind his house. He advises you strip naked as otherwise you will startle it.
Catching the rabbit is merely a matter of putting the trap in one of you quick slots and the clicking on the rabbit.
Talking with @Stanley Xavier Hippington again, he asks you to take the rabbit to the @Dr. Tristan Fenwick of @The Zoological Society in @Tarant to authenticate it.
If you talk to @Myrth about the blue rabbit he merely laughs at you.
Returning to @Tarant and talking with @Dr. Tristan Fenwick, he merely laughs at you and tells you to go visit @H. T. Parnell's Museum of Curiosities.
You can get the pelt from him by:
Buying if for 2000 (you can knock this down to 1250 depending on your skills)
Stealing it while he is asleep
Convincing him to give it to you (and pretend it has been stolen).
Upon returning to @Stillwater, @Myrth will tell you the location of @Qintarra if you give him the pelt (depending on your skills you can tell the truth how you found it or spin him a tale of heroism).
He also has the @Amulet of N'Tala on him. (The one the healer in Shrouded hills, @Gaylin was looking for). Another way of finding @Qintarra is getting the amulet (via thievery or combat) and taking back to the healer in @Shrouded Hills who will then tell you its location.