Deep Blue is the first book of the Waterfire Saga by Jennifer Donnelly. It starts with Serafina, daughter of Isabella, Regina of Miromara, has been raised with the expection - and burden - that she will someday become the ruler of the oldest civilization of the merfolk. On the eve of the Dokimí ceremony, which will determine if she is worthy of the crown, Sera is haunted by a strange dream that foretells the return of an ancient evil. But her nightmares is forgotten the next daddy as she diligently practices her songspell; eagerly anticipates with her best friend, Neela; and anxiously worries about Mahdi, the crown prince of Matali, and whether his feelings towards her and their future betrothal have changed. Most of all, she worries about not living up to her mother's hopes.
The Dokimi proceeds, a dazzling display of majesty and might, until a shocking turn of events interrupts it: an assassin's arrow wounds Isabella. The realm falls into chaos, and Serafina's darkest premonitions are confirmed. Now Serafina and Neela must embark on a quest to find the assassin's master and prevent a war between the mer nations. Their search will lead them to other mermaids heroines scattered across the six seas. Together they will form an unbreakable bond of sisterhood as they uncover a conspiracy that threatens their world's very existence.
A group of river witches, the Iele, are chanting in a circle around a waterfire. Their chanting is revealed to be a prophecy, calling six mermaids to come together and defeat an evil monster before it is too late. The mermaids must go to the River Olt in the black mountains, where the leader, Baba Vraja, will explain everything to them.
In Miromara, it is the day of Serafina's Dokimi. Serafina wakes up from her dream to her mother, Regina Isabella, berating her about her duties. They argue, and Isabella leaves. Thalassa, the canta magus, comes to help Serafina practice her songspell, but Serafina is unable to focus, worried about the rumors that she has heard about Mahdi. Sera's best friend, Neela, arrives and they sneak out of the palace. Neela is telling Sera about a weird dream she had when they find Mahdi and Yazeed asleep under a huge coral after a night of partying. Sera realizes that Lucia Volnero had been right and that Mahdi had changed. She leaves, feeling betrayed. Back at the palace, Sera overhears a conversation between her mother and Vallerio, her uncle. They are discussing the prospect of a war between the mer realms and the importance of the Dokimi. Sera resolves to make her mother proud.
The Dokimí begins. The first part of the ceremony is the blooding, where the bronze monster Alítheia tastes Serafina's blood to determine if she is truly a descendant of Merrow. Sera passes easily and starts her songspell. She sings of the history of Atlantis and her hopes for the future. Right as she is finishing the sonspell, her mother is shot with a poisoned arrow. The Kolisseo is in chaos, and Sera and Neela are escorted into the stateroom, where Isabella is dying. Sera and her mother are able only to exchange a few parting words before a Blackclaw dragon attacks. The princesses escape out of the palace, but they are captured by Markus Traho, who has also captured Thalassa. Sera and Neela realize that they had the same dream about the Iele and are both part of the six mermaids. The Praedatori arrive and help them escape, but they are ultimately overtaken by Traho and his men. Thalassa decides to sacrifice herself so that Serafina and the rest can get away safely.
Sera, Neela, and the Praedatori arrive at the palazzo of Duca Armando, leader of the Praedatori. From him, Sera and Neela learn that the attack on Miromara was done with the help of a human named Rafe Iaoro Mfeme. They spend the night there with the Praedatori, but Traho catches up to them and attacks the palazzo. Duca Armando is killed and Blu, a Praedatori, gets injured. Sera and Neela are able to escape by swimming through a mirror, but they end up in the Old River instead of the Olt River. There, they meet Ling from Qin, who reveals that she is also on her way to meet the Iele. As they swim, they pass a couple of villagers who cheer for Serafina, which prompts Ling to talk about the likelihood that Serafina's mother is dead. Sera gets angry and swims off to go shoaling.
But as she is shoaling, suddenly, a fishing net surrounds the shoal and starts hauling them, and Sera, up. Ling gets trapped in the net while trying to save Sera. She is brought with the shoal onto a ship, which Sera discovers is piloted by Rafe Mfeme. Thankfully, the Wave Warriors, a land version of the Praedatori, arrive and Mfeme is forced to drop the net back into the ocean. The mermaids are reunited and spend the night at a catfish lady's house, where Neela makes new disguises for them as swashbucklers.
Ava from the Freshwaters, Becca from Atlantica and at the Iele's caves, Astrid from Ondalina. When they arrive at the Iele's cave, they are given the mission to kill Abaddon and save their underwater world. Astrid thinks its a joke and leaves while the rest stay and train. However, the caves are attacked so the remaining five perform a bloodbind and escape through a mirror.
Daughter of Merrow, find the five
Brave enough to keep hope alive.
Thus has no choice but to deceive.
Together find the talismans
Belonging to the six who ruled,
Hidden under treacherous waters
After light and darkness dueled.
- The book cover is Serafina swimming away from Cerulea
- Bea Miller did the audio book of this book
- Open Your Eyes by Bea Miller is the song about the saga and in honor of the book release.