Ana Dakkar is a freshman at Harding-Pencroft Academy, a five-year high school that graduates the best marine scientists, naval warriors, navigators, and underwater explorers in the world. Every year, the freshman at Harding-Pencroft are taken on a weekend trial at sea, and Anna can only hope she has what it'll take to succeed. But all her worries are blown out of the water when, on the bus ride to the ship, Ana and her schoolmates witness a terrible tragedy that will change the trajectory of their lives.

After the horrific event, the professor accompanying them informs Ana that Harding-Pencroft and their rival school, Land Institute, have been fighting a cold war for a hundred and fifty years. Now that cold war has been turned up to a full broil, and the freshman are in danger of becoming fish food. In a race against deadly enemies, Ana will make amazing friends and astounding discoveries about her heritage as she puts her leadership skills to the test for the first time.