This quest is not available in game.
Return to Jaedenar and kill the succubus Rakaiah before finding the Remains of Trey Lightforge.
She would like to pretend that she's fine. She'd love for me to think that she's strong enough to deal with all of this on her own, but I know better than that. Trey's death and hearing the torture he was put through is going to haunt her for a long time, and there's nothing we can do to stop that. But we can give her some peace!
<name>, return to Shadow Hold, kill Trey's torturer and find his remains. There is no reason we can't tie off all these loose ends while Arko'narin mourns in her own private way.