Cody knows there are many mysteries in the big, wide universe. Like why it hurts so bad to get stung by a yellow jacket and how some things can only be seen with a microscope. Or the exact moment when her best friend, Spencer, will finally arrive with his parents and move into her neighborhood for good! But the biggest mystery of all may just be Mr. Meen, Grandma Grace's next-door neighbor. No one has ever seen him, and when a "Welcome Home" sign appears in his window, Cody and Spencer can hardly wait to see who shows up.