Martha's best friend is an alien. Opal Moonbaby can move things with her eyes, make popcorn fountains, and travel all over the world in her very own spaceship. Martha can't imagine life without her. But Opal's time on Earth is almost at an end. They have one final summer together. So why is Opal acting so strangely all of a sudden? A madcap story of friendship, fun - and aliens! If you love Jacqueline Wilson, Cathy Cassidy or Liz Kessler, you'll love reading about Opal Moonbaby.