To start this quest read the signpost north of the varrock general store. When you will attempt to do this the mysterious old man will appear and teleport you to a city. He will then tell you that this the city of the random events, Randomevenity, and that when you will get next time a random event you will be teleported to this location. Then he will ask for your help to stop Evil Bob and the Evil chicken to conquer it. If you accept the quest he will put you to go to the Evil chicken's base, using the portal that is located in the east of the city.