There is - by certain unreliable and maddening accounts, and now by your own dreadful experience - a city on the eastern seaboard of the United States, in northern Massachusetts. You do not recall seeing it on maps when you were growing up, and no-one of your acquaintance ever admitted coming from that place until you found yourself living within its eerie confines. It is a city of windowless, cyclopean skyscrapers, of crumbling baroque buildings, and ruins that must, impossibly, predate human habitation in this part of the world. At times, you can see remnants of familiar small towns which have grown together into this monstrous conurbation - Dunwich in the west, beyond Sentinel Hill; quaint Kingsport, by the sea; industrial Innsmouth, the engine of trade and commerce; and the city`s heart, Old Arkham. You know that this city is monstrous, and its government in the thrall of - or in league with - alien horrors. You know better than to go out at night, when the clouds roll in from the sea and shapes move in the sky. You know there are occasional, unpredictable streets that come and go according to some unearthly schedule, that strange black ships dock at Innsmouth to trade with the squat, ugly denizens of that neighbourhood. You know, too, that not all of your neighbours are sane - or human. But you`re trapped. There`s no way to escape the city. Because the city is the world. Cthulhu City is a setting for Trail of Cthulhu, usable for a full campaign in its own right or as a nightmarish intrusion into an existing game.