Ana Dakkar is a freshman at Harding-Pencroft Academy, renowned for producing the best marine scientists, naval warriors and underwater explorers in the world.

But, unlike the other students, the water is personal for Ana. After losing both of her parents on a scientific expedition, her older brother Dev is now the only family she has.

Ready to prove herself, Ana and her class are off to a top-secret weekend trial at sea.

But, on the bus ride to the ship, Ana and her schoolmates witness a terrible tragedy that will change the trajectory of their lives forever.

Rick Riordan's trademark humour, fast-paced action, and wide cast of characters are on full display in this undersea adventure.