Winifred, Eugene, and baby Bun Bun are off to visit their uncle, who lives in the Castle Apartments. What could be more thrilling for a little girl who is enchanted by princesses?

When Bun Bun, who's just learned to walk, totters into an elevator alone, big sister Winifred comes to the rescue. As they go up and up and up in the modern-day tower, they have adventures fit for any princess: an encounter with a hairy monster, a scary witch, and even a beautiful princess. Or do they?