In any city, in any country, go to any phone-box you can get yourself to. Make sure that you do this about fifteen or twenty minutes past midnight, and that nobody is accompanying you or watching you. Enter the phone-box, close the door, pick up the receiver, and touch nothing else. Hold the receiver to your ear and whisper, "I wish to meet the Holder of Nightmares." After a minute, if no voice has replied, leave the phone-box as fast as you can. Do not question why.
If you hear a man's voice reply in a language you do not recognize, then you have succeeded. Close your eyes and do not move. You should feel a sort of pressure close over you, and then the sudden sensation of falling. Should you open your eyes while experiencing this, you will find yourself lying outside of the phone-box, with your arms mangled and their flesh torn apart.
If you manage to keep your eyes closed, you will feel yourself land softly onto what feels like a chair. Feel free to open your eyes. When you do, you shall see that you are in a small room, filled with a thick smoke that goes up to your waist. In front of you is a four-poster bed, upon which an item will lie. The item will be different for everyone that enters this room. Whatever it is, pick it up, and hold it tightly in the hand you use to write with.
Get into the bed and sleep -- an easy task, as the fog will make you feel tired when inhaled. As you lie in this bed, you will dream of unspeakable horrors, which will become more twisted and grotesque as they progress. As long as you keep the item in your writing hand, you shall be protected. But if, as you dream, you feel some sort of force prying the item from your hand, say loudly, "I mean no harm; I only wish to meet the Holder of Nightmares." The horrors of your dreams are nothing compared to what you will face should the item leave your hand.
Your final dream in that bed will be near-lifelike. You will be standing in front of the person you love most. Do not look into their eyes. Do not hesitate for too long, or your quest shall end here, and you shall be stuck watching nightmares for the rest of your existence. Take the item you picked up from the bed, and beat the person to death with it - at this point, it will have turned into a metal pipe or a wrench.
When the bloodied body at your feet stops moving, close your eyes for a few seconds, and then open them again. The person you just killed will appear as an old man, his grey hair and beard matted with blood, his skull fractured and broken. This is the Holder of Nightmares. Keep your weapon in your writing hand, and push your other hand onto his heart.
You will find yourself standing in the phone-box, with its receiver ripped off the cord and held in your hand, in place of your weapon. Walk away from the phone-box and watch, if you want, as it destroys itself. The glass will break, the coin box will crumple, and the phone-less cord will whip itself through the air.
The phone in your hand is Object 149 of 538. Do not let dreams stand in your way.