Following the sinking that shattered Atlantean culture, Kida has risen to become queen and has chosen to stay in Atlantis, having married Milo Thatch. Together they work to revive the city, wielding the Heart of Atlantis to rekindle a civilization that once thrived beneath the waves. Their effort draws in Milo’s former allies and the aging statesman Whitmore, whose arrival in Atlantis is both a welcome reunion and a sign that old friendships can still matter in the face of a new danger. The Atlanteans warmly embrace their visitors, yet the guests bring alarming news: a mysterious surface threat is terrorizing ships and cargo, casting a shadow over the city’s fragile rebound.
As they investigate, the group travels to Trondheim, Norway, where the threat appears to be a fearsome creature that seems to belong to legends. At first, the team suspects an ancient Atlantean war machine might be behind the trouble, a relic hidden in plain sight for centuries. Their suspicion shifts, however, when they uncover a more intimate puppeteer: the town magistrate Edgar Volgud, who appears to be in league with the creature. Yet the truth runs deeper—the Kraken itself has become the master, and it has bartered with Volgud to sustain the town for as long as possible, trading lifespans and souls for the lifeblood of the village.
A fierce confrontation follows, culminating in a dramatic blow that destroys the Kraken. With the beast gone, Volgud’s immortality collapses in an instant and he disintegrates, allowing the village’s spirit to be restored and the people to reclaim their future. Throughout these perilous trials, Kida continues to grow, learning more about the wider world beyond Atlantis and gradually accepting the possibility that her people’s power could be shared rather than hidden. Yet she remains mindful of the risk that other Atlantean war machines could be out there, somewhere beyond the horizon.
Their journey then leads them to the Southwestern United States, where coyote spirits figure prominently in the unfolding mystery. In a hidden Arizona city adorned with Atlantean architecture, the crew discovers remnants of a vanished Atlantean outpost. A cunning shop owner, Ashtin Carnaby, tries to loot this sanctuary for himself, but the spirits respond decisively, transforming him into one of them and preventing him from profiting at the expense of history. The wind spirit Chakashi entrusts Kida with the sanctuary’s guarded knowledge and reminds her that Atlantis’ destiny lies in her hands.
Upon returning home, the group faces a new and more personal threat: Erik Hellstrom, once a rival of [Whitmore], has gone mad with power and believes himself Odin after a devastating stock-market crash. He steals one of Whitmore’s ancient treasures, the spear Gungnir, and the pursuit takes them to the frost-kissed Nordic Mountains. Hellstrom—convinced Milo is Loki and Kida is Brunhild—casts Milo, Mole, Vinny and Audrey out of the realm of Asgard, kidnapping Kida in the process. Hellstrom’s apocalypse plan includes the creation of a lava beast and an ice beast to usher Ragnarok, a cataclysm he believes will reset the world.
Vinny’s quick distraction of the monstrous duo buys just enough time for Kida to reclaim the spear and turn the tide against the primal threats. As the pieces fall back into place, Kida grasps the true power of the Atlantean Crystal and what it means to share its potential with humanity. She shoulders the responsibility with resolve and, combining the Spear with the Heart Crystal, lifts Atlantis from the sea, signaling a new era for the city and its relationship with the world above. In a closing narration, Whitmore reflects on how those choices changed the planet for the better, hinting at a future where Atlantean power can contribute to a broader, brighter future for all.
