At the end of Dark Tide, Book 3 in the Waterfire Saga, Astrid leaves her mermaid friends to confront her ancestor, Orfeo, the evil force behind the rise of the monster Abbadon. Orfeo possesses one of the talismans that the merls need in order to keep the monster locked up forever. But without the ability to songcast, how will Astrid be able to defeat the most powerful mage in history? Meanwhile, Serafina and her Black Fins train goblin troops for battle against her uncle Vallerio's death riders. Will Sera ever see her beloved home--and her beloved Mahdi--again, or will the Volneros take over the mer realms while Orfeo takes on the gods themselves? Nothing less than the fate of the underwater world is at stake in this breathtaking finale. Praise for Deep Blue

"A richly imagined novel. Themes of conquering fear and believing in oneself are woven throughout, along with an acknowledgment of humans' environmental impact on the sea and its inhabitants. Despite the high stakes and a few frightening moments, the story is never over serious; it's just right for readers who have grown up with, but aged out of, The Little Mermaid and the Disney Fairies franchise."
- Publishers Weekly

"A fantastic addition to the genre of mermaids, this book will also appeal to readers of action and those who appreciate usurped leaders taking back their kingdom. It starts with a common enough concept: a royal girl who is worried about her betrothal and about love. Donnelly then adds layers of complexity to the tale and weaves her story into that of Atlantis. Friendship, trust, and responsibility are major themes as Sera struggles to grasp that she is really her kingdom's only hope. Quick-witted, loveable characters and a well-planned fantasy world make this an all-encompassing book. Readers will eagerly await future volumes and the answers they will provide."
- VOYA

"Best-selling Donnelly (Revolution, 2010) builds an alluring mermaid civilization and history, filled with painterly descriptions of Sera's underwater palace and its unearthly architecture, her sumptuous wardrobe, and the menagerie of half-human, half-marine animal denizens. There's also plenty of romantic tension with handsome mermen, strife between merls (that's girl mermaids) from rival regions, and some powerful female friendships amid the fast-paced plot, filled with wondrous magic."
- Booklist