Trail of Cthulhu Preparedness Explained

Do the investigators need a car to pick you up in a desolate spot in the woods? A player can make this happen by a) supplying a credible retroactive explanation of how she arranged it, and b) scoring a Preparedness success.

A point of some contention in the Trail of Cthulhu games I've run is the preparedness skill, because of my own childish desire to say "no" to perfectly reasonable players. That's my flaw, not yours.

Robin D Laws, GUMSHOE system creator, explains Trail of Cthulhu preparedness and puts me in my place.