Agana Taitano Hofstadter is a brilliant expert in cryptanalysis. She is working, under the Clean Blue Project of the Great Restoration, to rid the seas of Earth-Ocean of the last of the chemical weapons that were dumped there over two hundred years ago. Taitano's dolphin mentor and professor informs her that, for unknown reasons, she has been summoned by the United Nations Commission for Ennean Cross-Cultural Exchange to the dark and inhospitable planet Ennea, whose only inhabitants are the enigmatic Enneans. Over one hundred years ago, the Enneans arrived in their interstellar vessel and saved Earth-Ocean from a massive solar flare; and yet communication with them is still a mystery. Despite Taitano's ongoing struggle to manage a debilitating psychological condition, she is persuaded by her cantankerous grandfather to follow her destiny and undertake this journey across the stars. Included in her team are an arrogant cybernetically enhanced human, an irrepressible dolphin doctoral student, and an artificial intelligence with a proclivity for holographic antics. When they arrive and begin their work deep beneath the sub-terranean Ocean of Ennea, this group of intrepid scientist-explorers uncovers a world-changing conspiracy. In a race against time, Taitano and her colleagues must work together to save the Enneans-and themselves-from certain destruction.