Ana Dakkar, a 15-year-old student at Harding-Pencroft Academy—a five-year boarding high school for marine sciences perched on a remote bluff along the southern California coast—navigates a life where curiosity and danger collide. As a new year unfolds, she shares a quiet moment with her older brother Dev, a 17-year-old senior, who gifts her their mother’s pearl necklace in anticipation of her fifteenth birthday. The day soon shifts from routine to peril as the entire freshman cohort — twenty students in total — travels to the nearby city of San Alejandro to compete in end-of-year trials aboard their school yacht, the Varuna, a vessel named for the sea god Varuna. The trials are overseen by their aging mentor, Dr. Theodosius Hewett, a figure whose presence and authority anchor the crew.
Barely underway, a volley of torpedoes erupts from a submarine at the base of the cliff, sending buildings tumbling into the ocean below. In the ensuing chaos, Hewett orders a rapid, coordinated retreat: the drones are deployed to survey the wreckage, the bus is boarded, and the students are redirected onto the Varuna and sent out to sea. He frames the attack as the work of a rival institution, the Land Institute, insisting that it is safer if the world believes the Harding-Pencroft crew perished as well. To ensure Ana’s safety, Hewett designates one of the boys, Gemini “Gem” Twain, to act as her bodyguard. What follows is a dramatic, adrenaline-fueled defense at sea as Land Institute seniors mount a bold kidnapping attempt on Ana.
The abduction is thwarted in large part thanks to a friendly bottlenose dolphin—Socrates—who intervenes and knocks the would-be captor, Caleb South, out of the water. In interrogation, Caleb openly revels in the destruction of Harding-Pencroft, claiming they did it to safeguard the legacy of an outlaw and to hoard technology that could change the world for the better. Hewett responds with ruthless practicality, casting Caleb overboard in his flotation vest and water wings, leaving him to drift with the others who have been dumped from the pontoon and left to fend for themselves.
Back on the ship, Hewett lays out a history that sounds like fantasy but is, in his telling, rooted in reality. He explains that Jules Verne’s beloved novels, 20,000 Leagues Under the Sea and The Mysterious Island, are partly fictionalized accounts based on Verne’s interviews with people connected to real events. Ana, it turns out, is descended from Captain Nemo (Prince Dakkar) and from a lineage that has dictated the arc of both academic factions. Nemo—whose genius forged technology ahead of its time—waged a guerrilla war against colonial powers in a past era, a struggle that now echoes through Harding-Pencroft and Land Institute as modern-day warfare over Nemo’s inventions. Hewett recounts how Aronnax, Ned Land, and Conseil—characters who appear in Verne’s narratives—formed a real-world backstory that influenced the founding of Land Institute, while Cyrus Harding and Bonaventure Pencroft, recalling The Mysterious Island, carried Nemo’s memory into a new institution designed to shield his inventions from misuse.
The trials on the sea were meant to be a first glimpse at Nemo’s technology, but in Hewett’s eyes the moment has arrived for full disclosure. Ester Harding, an orphan and Cyrus Harding’s distant descendant, had learned of these truths months earlier but was sworn to secrecy. As the stakes rise, Hewett reveals a crucial detail: long before the era of genetic science, Nemo learned to biometrically link his most powerful inventions to his own genes so that only he or his direct descendants could operate them. That means Ana—the purported last surviving direct descendant—holds the key to wielding Nemo’s legacy.
Yet Hewett’s health is failing; he is secretly battling advanced pancreatic cancer and is found unconscious in his cabin on the second day at sea. Seizing the moment, Ana takes command of the Varuna and uses one of Nemo’s inventions to chart an unseen course toward a distant beacon in the Pacific—Lincoln Island, the very place where Nemo and his companions once survived and where Nemo died aboard the Nautilus. To reach this hidden refuge, they must decipher a coded path and send back a reply that will unlock the island’s defenses.
Touchdown at Lincoln Island brings a quiet, almost surreal welcome. Luca Barsanti and Ophelia Artemesia greet the crew as caretakers descended from the island’s storied past, joined by Jupiter, a clever orangutan who has learned to cook by watching a modern cooking competition. Hewett begins receiving treatment through Captain Nemo’s medical technologies, and Luca and Ophelia introduce the students to the Nautilus. The ship, now a near-pristine specimen of artificial intelligence, sits dormant at the bottom of a lagoon for centuries, its legend intact after Nemo’s time. Ana boards the Nautilus with ease, speaking in Bundeli, the ancestral language she shares with Nemo, and activates the ship’s functions by playing a pipe organ that Nemo had installed on the bridge.
The peaceful interlude is shattered when the Land Institute team—who pursued them in their submarine, the Aronnax—arrives on Lincoln Island. A fierce battle erupts as the Aronnax closes in, and the truth about Ana’s brother Dev comes to light: he survived and has aligned with Land Institute, now commanding the Aronnax and broadcasting a warning to evacuate. In a devastating personal turn, Ana discovers that Dev has embedded a tracking device in the necklace he gave her. She destroys the device and fires up the Nautilus’s propulsion to flee. In the wake of the pursuit, the ship crosses the western Pacific, edging near Palau and meeting a remarkable giant octopus the crew names Romeo, which Ana befriends with the help of a keytar and the ship’s AI.
With Romeo as their unlikely ally, the crew speeds back to Lincoln Island, where a brutal clash resumes with the Aronnax. The battle ends with the Aronnax overwhelmed—Romeo’s mighty strike sending the ship’s crew into improvised jail cells—and a personal confrontation between Ana and Dev that culminates in Ana knocking him unconscious with rubber bullets.
In the aftermath, the Harding-Pencroft ninth-graders, Luca, Ophelia, and a recovering Hewett vow to rebuild their school and to safeguard Nemo’s legacy from those who would weaponize it. Ana, bearing the weight of her family’s choice and destiny, escorts Dev to the lagoon near the wreckage of the Nautilus, where their parents’ final resting place awaits, a somber reminder of the cost of power, loyalty, and a history that refuses to stay buried.
