The front door note is the first indication Kaitlin Greenbriar receives to suggest that something is amiss up on arrival home. It is a letter addressed to her from her younger sister, Samantha Greenbriar, urging her not to try and find her, and to especially keep it a secret from everyone, including their parents, Janice and Terrence Greenbriar.
I'm sorry I can't be there to see you, but it is impossible. Please, please don't go digging around trying to find out where I am. I don't want
Mom and Dad anyone to know.
We'll see each other again some day. Don't be worried. I love you.