From the Rulebook:
You and some friends will tell the story of your other selves in the world of Spider’s tapestry, who are awake enough to use the magic of Words. This world can be whatever you want it to be: it can be like today, or like some point in the past, or even an entirely created world. All of the players should discuss and come to agreement on this. You should also agree how many acts you want to include, like the acts of a play, which are made of any number of scenes.