Appearing before the head of the Academy for fighting at her graduation ceremony, puffer ship navigator Tia Grom-Eddy must either join the crew of a spaceship on a deep space mission or complete a lengthy probationary period on Earth. Mortally afraid of travelling into deep space, Tia chooses probation. Estranged from her parents, Tia is bereft when her sister, Leilani, joins the crew of a puffer fish spaceship sent to investigate a whirlpool in deep space. And when the cosmic whirlpool sucks Leilani's shuttle into its grip, Tia must overcomeher fear of space travel and find a way to work with her mother, who is leading the rescue, or risk losing her sister forever.