High above earth in a low orbit facility, an experimental clean energy project known as Erebos-which taps into the vacuum structure of space-destabilizes and is jettisoned into the planet's atmosphere. Far below, unaware of the danger rocketing toward her, nineteen-year-old Sasha Kino goes night surfing to clear her head after a fight with her father. When Erebos crashes into the ocean the device fuses her DNA with that of an orca and Sasha is altered beyond recognition. She is stronger, can hold her breath longer, and can swim deeper and faster than any creature on the planet-but her newfound abilities may come at the cost of her humanity. Captain Alric Jager, head of the U.S. Navy's Special Projects Division, is sent to clean up the Erebos situation. But when Jager learns of what the device did to Sasha he decides to steal them both. Driven by a dark and twisted legacy, Jager is determined to create the ultimate super soldier - no matter the cost.

Torn between the land and the sea, and ruthlessly hunted by Jager, Sasha must rediscover who she is and for what she is willing to fight.