This quest is started by William Pestle in Goldshire's inn.
Description:
My brother Morgan is waiting in Stormwind for my shipment of candles. I don't have enough time to make the trip myself, but if you'd like to take him the shipment, he'll pay you well.
I've packed up the candles, and you can find Morgan in our shop, Pestle's Apothecary, in the Stormwind Trade District.