Eleanor Tweedy, an eccentric inventor killed in a tragic accident in 1938, leaves her inventions behind in her childhood home. They are in the form of marbles, and were inspired by a mysterious marble game given to Eleanor as a child. Now, an anxious raven and a grouchy, grey cat lead another child living in Eleanor's home to two translating marbles, and from there to the Marble Board with it jar of marbles, large and small. The child's name is Katie, and she and her friends realize the Board and its marbles represent the solar system on the left and the Jupiter system of moons on the right....