Once Upon A Time, all gone wrong

Winona Willamina Wattz, a young girl living in southern USA she loses her older sister Melody, leaving the five children with distraught parents and forcing two home from college to take care of the younger three.
After a year the family uproots to a new town, it's a nice quaint small town and they quickly know most of the occupancy. So when a snow day arrives, well Winona does what any sinsable child does, she goes sledding down her drive way.

However, when the sled won't stop as it hurtles through the woods Winona has to make an escape, but where she lands is not the snow covered forest floor she had seen seconds before. What happens when Winona finds out new things about her sister Melody? What was she doing in this place? How was she getting there? How did she get back and forth? And how would Winona do the same?