Palace of the True Rat King

You ask the bartender who this "True Rat King" is. He laughs.

"You must be new here! Why, the Rat King is the owner of this here bar! That one in the city up there is an imposter who banished the true king to the sewers!"

You see a strange fervor in his eyes. 

"If you'd like to meet the True King, the line's in the back. You won't regret it."

He stares at you expectantly, even as another patron down the bar tries to get his attention.