Rat Burgiss is a member of the Varrock Palace Secret Guard. He is found at the crossroads south of Varrock and north of Lumbridge (east of the Champions' Guild) at the point where the roads split just north of Al Kharid's open pit mine. To find him, just home teleport to Varrock and follow the road south.
He is the starting point for the What Lies Below quest. If players do not have the requirements for the quest, Rat Burgiss will say that he is very busy and cannot chat. If players have the requirements to start the quest, he will ask the player to get his stolen papers back to full folder and deliver the Letter to Surok to Surok Magis in Varrock palace library.
Rat is also one of the three NPCs involved in the Varrock Tasks, and he will give the easy reward. However, it is not possible for free-players to speak to him at this time.
Members who have completed the Easy section of the Varrock Tasks have the option of talking to him and changing their Varrock Teleport to land at the south entrance of the Grand Exchange instead of the centre of Varrock Square.