Investigate a rock where the vampires sacrifice grinnins at ( 52, -22, -100 ) Copy/waypoint 52, -22, -100 on the second floor.
Investigate a pit of bones at ( -68, -25, -55 ) Copy/waypoint -68, -25, -55
Investigate the area near a pit with a large gathering of vampires, at ( -75, -32, 75 ) Copy/waypoint -75, -32, 75
At the third location V'Narys, a level 35^^^ vampire, and his three henchmen will spawn and attack you. Kill V'Narys and loot his corpse to get a sealed letter.
Note: Make sure all in your group get close enough for the auto-update for the pit before V'Narys dies. If not, when they do get the auto-update they will get a different quest step that says "I need to revisit the Landmarks to see if the Vampire Leaders are aware of my presence" or something like that. All it means is you have to wait for V'Narys to respawn. Run around and kill stuff if you like, he'll find you when he spawns. You don't actually have to revisit anything. When he does catch up to you, he will aggro on one of the group that didn't get the update the first time, so if they're cloth wearers, you'll want to be ready to taunt him off fast.