Synopsis: Kids vs. parents! An epic treehouse sleepover! An awesome group of friends! An exciting new book from National Book Award finalist Lisa Graff.Winnie's last day of fourth grade ended with a pretty life-changing surprise. That was the day Winnie’s parents got divorced and decided that Winnie would live three days a week with each of them and spend Wednesdays by herself in a treehouse between their houses, to divide her time perfectly evenly. It…