Ok, it starts out at the Freeport Milita HQ. You need to kill a Dervish Messenger in the Yapping Maze (grey to low green to 19). You return to one of the captains in the milita hq and are given the choice between bezerker and guardian. If you pick guardian you're told to head down to the serpent sewers (reached through the thieves way) and protect an informer in a storage room. The trip is apparently not possible for a solo 19 warrior - too many aggroing group greens in the way.
Anyone actually know where the room is? Anyone know what the encounters are? Should I bring a group or am I going the wrong way through the sewers? The Quenos quest suggests there will be an instanced zone where only the warrior can enter - kind of a pain in the butt if I need to drag a group along just to abandon them.
Your help appreciated