Delivery to Tranquillien is the final part of the 'Missing in the Ghostlands' quest chain, which introduces the young (blood elf) hero to the Ghostlands after completing the Eversong Woods quests.
I... I'm too weak to continue. I carry a dire warning from Regent Lord Theron, in the form of a letter. You'll have to deliver it for me.
Take it to Arcanist Vandril in Tranquillien. You'll find the town further to the south along this road. Go there and... find Vandril...
You have the letter?
Finally! We've waited for a response from the regent lord for weeks! Let me see here...
<Vandril begins to read the letter.>
What's this? A dark presence? He senses a dark presence in the Ghostlands?! No kidding; I could have told him that!
This is what we've been waiting for?
You will receive: