Lu watched the love of his life walk the plank and sink into the inky-black depths of the sea. Nnenna was dead . . . or so he thought.

Five years later, Lieutenant "Lu" Ortega, dutiful fleet officer, embarks on a mission to hunt down a powerful talisman now in the hands of a runaway mermaid. On his quest, he discovers the impossible: Nnenna is still alive. Fierce and cunning, and as breathtaking as ever, Nnenna's won enough bloody sword fights as a pirate captain to earn the nickname “Devil of the Deep.” She has come to reject the system of order that Lu clings to, and worse, she's protecting the very quarry he's tracking: Pearl Highwater, who has defied the all-powerful sea god and might hold a valuable key to finding her people's lost island.

When the tides and fates bring them together, Nnenna, Lu, and Pearl must choose their loyalties, find their courage, and race to protect the island from false gods and forces of evil— or risk unleashing an ancient curse that could destroy them all.