I'm Elsie, from the planet Caelum. It's 96% ocean, but that's okay. Out of all six planets (or seven, if you believe the myths), we're the only people with gills. I can breathe underwater for minutes at a time, discovering the secrets of the deep-sea. Diving is my first love. But not everybody understands. Each year they run a competition-a single black pearl is dropped into the ocean, and graduating students dive to find it. It sounds easy, but it's...