I can't imagine a parent of a child with special needs sleeping through said child making her way down the stairs and perhaps out of the "cabin" without waking, or into the bathroom at the bottom of the stairs, for that matter. I have several dogs and if they get up to go potty outside in the middle of the night, I hear them. Aren't parents kinda trained with those parent ears to hear their kids, especially one with special needs? For several of the possible scenarios being discussed here to be accurate, Nora would have had to have made her way down the steps and then out... w/o either parent waking? And the whole family is not at home, but in a strange, (i.e., new) setting on top of it all.