This movie came on HBO in the 1980’s, probably around 1987. It was about a little boy and a little girl, possibly a brother and sister. Some men in a car attempted to kidnap them, they got away and ended up running into the woods. While in the woods they came across this old gnome, he lived in a tree house. The kids were sliding down vines I think, while escaping the kidnappers. I know this isn’t much to go on, but I only saw part of the movie. I thought it was a cool movie when I was little and would love to find it again to share with my own kids. Any suggestions appreciated!