In any city, in any country, go to any mental institution or halfway house you can get yourself to. Ask at the front desk to see someone who calls himself “The Holder of the Cost.” The worker will sigh, – sounding as though the weight of countless eons bore down on their shoulders – wearily exit from behind the counter, and trudge towards the interior of the building. Follow them.
They'll make many turns and take you down many hallways – more than should fit in a single building – before stopping and opening a door for you. Inside will be a rotting wooden staircase down through a moist, earthen tunnel. Begin your descent; the worker will shut the door behind you, leaving you in total darkness. Even if you have a flashlight, you probably don't want to turn it on. Keep your hands off the walls, and walk. With every step you descend, you will feel a weight on your shoulders. The weight should very quickly become a crushing burden, and it's a long way down.
If you reach the bottom without being suffocated by the burden, you'll find that the stairs lead to an underground rotunda, a circular room with a domed ceiling. Here, too, the walls and floor will be made of dirt, dripping occasionally. That's not water, by the way.
The ceiling will have a small round hole in it, through which sunlight will stream down upon an ancient man sitting in a luxurious red fur chair in front of a wrought-iron table. In his hand, he clutches a plain stainless-steel kitchen knife. Even if he's awake, he'll be too weak to offer any resistance as you take it from his scarred hands and slit his throat.
You may feel a stinging sensation across your own throat as you do so; take a look in the full-length mirror across from where the man died, and you may notice a thin cut along your throat healing over, if you're fast enough. Steady yourself against the frame as a wave of dizziness washes over you.
If the old man had been awake, you could have asked him, “What will it cost to stop Them?” And he would have told you just what you were getting into. The cost is high, though, so very high and so horrible to contemplate that you almost certainly would have lost your mind and ended your journey on the damp floor in front of him. Even if you hadn't, you certainly would not have taken the knife, having known. When the dizziness passes, remove the mirror from the wall and ascend the staircase behind it.
That knife is Object 144 of 538. It will cut anything, but with every use, you will feel its bite.