In four weeks, Atlantis - the prize jewel of Ancient Greece - will slip under the glittering surface of the Aegean Sea. But 16-year-old Artemis doesn't know that yet.

She's more concerned with her impending engagement to Troy, the son of her family's archenemy. Artemis has enjoyed a life of privilege on Atlantis, but debts have swamped her home life. Her marriage has been arranged by her parents, who hope the union will put to rest the feud between their families. Artemis desperately wishes to chart her own course, but her loyalty to those she loves complicates her yearning for freedom.

When a boating accident plunges her into the arms of Egis, an enthralling merman from the undersea kingdom of Aegon, Artemis learns of Atlantis's doomed fate. She must decide whether to follow her head or her heart as she races against time to save the lives of her fellow islanders before Atlantis sinks into the sea forever.