Select 'Cyclone Street' from the map choices and load it into the map. You do not need to bring any other equipment or any other players.
Go into the house and follow through the living room. You will enter the Old House corridor and turn to your left as soon as you enter this area. There will be a deer mounted on the wall.
Say "I want to join the cult" to the deer. It may take some repetition. It will then turn red and music will play. The deer will tell you to find the key (which you don't need to) and the achievement will unlock after it has finished speaking.