Buy a bat ride to the Undercity from the bat master Karos Razok, then take Podrig's Order to Gordon Wendham in the Undercity.
One of my bats can take you to the Undercity, for a small fee. Speak with me again when you are ready so that we may arrange your transport.
You will find Gordon Wendham in the Trade Quarter of the Undercity. That is the same quarter where my bat will land.