Ada and the team serve up smart ideas to help Arthur tackle a tough tennis opponent. But the biggest win of all? Convincing him to keep an open mind!

While investigating a "monster" at the creek, the kids discover something even scarier: tons of yucky trash! Can they build a machine to clean it all up?

NASA thinks there might be a ninth planet on the edge of our solar system, and Ada and her friends are determined to help them find it!