In the mysterious dawn of 1880 Edinburgh, Professor Sir Oliver Lindenbrook, a prominent geologist at the University of Edinburgh, receives a captivating gift from his dedicated student, Alec McEwan — a volcanic rock brimming with secrets from a forgotten era. This intriguing token ignites a thrilling quest as Lindenbrook and Alec set off on a perilous journey to decode its secret message, retracing the steps of Arne Saknussemm, a pioneering scientist who, almost a century earlier, managed to navigate the harsh terrains of the Snæfellsjökull volcano in western Iceland. Once they decipher the inscription, Lindenbrook’s ambitions soar as he aims to replicate Saknussemm's legendary feat and embark on a descent into the very core of the Earth.
However, trouble looms as Professor Göteborg, fueled by an unquenchable desire for discovery, learns of Lindenbrook's ambitious plans and seeks to beat him to this monumental undertaking. This rivalry ignites a thrilling cat-and-mouse chase as Lindenbrook and Alec make their way to Iceland, only to find themselves captured in a dank cellar by Göteborg and his assistant. Their predicament takes a twist when they are dramatically rescued by Hans Bjelke, a local guide, and his devoted companion, Gertrud the duck. This surprising intervention unveils a dreadful truth — Göteborg has met his end, and signs indicate he was poisoned with potassium cyanide.
Göteborg's widow, Carla, initially distrustful of Lindenbrook, gradually uncovers the tragic truth behind her husband’s demise and agrees to ally with him. Armed with essential tools, including Ruhmkorff lamps, she insists on protecting her late husband's legacy. Though Lindenbrook is hesitant about her presence, he acknowledges its potential to be both a blessing and a curse.
As the expedition gears up, the team marks the perfect spot where the sunrise kisses Snæfellsjökull, heralding the start of their daunting journey into the depths of the Earth. Little do they know, lurking in the shadows, Count Saknussemm, a descendant of Arne Saknussemm, is covertly tracking their every move, driven by an entitlement that compels him to reach the Earth's core first.
Events take a turn when Alec inadvertently separates from the group and encounters Saknussemm. When he declines to assume the role of Saknussemm's deceased servant, who succumbed to exhaustion, he is met with violence — a gunshot wounds Alec in the arm. The echo of the shot alerts Lindenbrook to their location, and a hasty, makeshift trial unfolds for murder. Although guilty, Saknussemm escapes execution thanks to the group's reluctance, reluctantly joining their expedition as an unwilling ally.
As the brave explorers venture further into the subterranean realm, they stumble upon an underground sea, a vast, alien expanse that challenges their resolve. Undeterred by the hazardous environment, they ingeniously construct a raft to traverse the perilous waters, narrowly escaping a family of enormous dimetrodons. Just when they think they're safe, they find their raft ensnared in a turbulent whirlpool, threatening to pull them down into the abyss.
Despite their exhaustion, they finally manage to reach the opposite shore, but their moment of rest is fleeting. As they drift off to sleep, Saknussemm's dark intentions loom nearby, leading to a tragic incident where Gertrud falls victim to his foul hunger. Haunted by grief, Hans confronts Saknussemm, but fate intervenes when a massive boulder cascade crushes the count beneath its weight.
In the wreckage, they uncover the ancient ruins of Atlantis, a submerged city filled with enigmas beyond their wildest dreams. Among the remnants, they discover the skeletal remains of Arne Saknussemm, pointing toward a volcanic chimney that could guide them back to safety. Yet, an imposing rock barrier threatens to impede their escape.
Lindenbrook's creativity shines as he devises a method to blast through the obstacle using gunpowder left by Saknussemm. The group seeks refuge in a vast sacrificial altar bowl, only to face a monstrous lizard emerging from the depths. However, before the creature can attack, an explosion releases a torrent of molten lava, entombing the beast in a fiery grave.
As they ascend buoyantly on the back of the bowl, engulfed by heat and flames, they finally break through to the surface as the lava plume diminishes. Weary yet victorious, they return to Edinburgh, welcomed as heroes for their valor and rigorous determination.
Despite the accolades, Lindenbrook declines the spotlight, choosing instead to lament the loss of their documented evidence while advocating for future explorers to embrace the spirit of adventure. Meanwhile, Alec finds joy with Jenny, and Lindenbrook shares a heartfelt moment with Carla, hinting at a blossoming romance and a promising future ahead.
