They were a way of generating sub-plot on the fly.
Cards are illuminati style, with outgoing arrows. They also have a number, from 1 to 6; and should be linked together only in order.
Each represents a type of event - so the 1's would open a plot with a discovery, then 3 might have some form of conflict - 4's were great because they were a 'you succeed in furthering the plot' type of thing, whilst sixes brought things to a conclusion.
The idea was you dealt them out at the start of a session, and the players threw them into the ring whenever they had an idea that fit, and the main action was a little slow.
An example was "2 - The open door" - "The door opens, and suddenly you can see the path that the clue has set" You could intepret this literally, or figuratively.
There were several sets of path cards - horror was the only one I saw. Great for introducing people to TroupeStyle? play.