On the distant planet of Montressor, a young boy named Jim Hawkins is captivated by tales of the elusive space pirate Captain Flint, renowned for his ability to strike swiftly and vanish without a trace while hiding his treasure on the legendary "Treasure Planet." Fast forward twelve years, Jim, now an indifferent troublemaker struggling with his father's abandonment, helps his mother Sarah manage the family-run Benbow Inn. Following a reckless skysurfing incident that leads to his arrest, Jim's life takes a dramatic turn when a spaceship, piloted by the mysterious Billy Bones, crashes near their home. Just before his demise, Billy entrusts Jim with a sphere and ominously warns him to "beware the cyborg"—a prediction that foreshadows the chaos to come as a band of pirates assail the inn. With his mother and their dog-like friend, Dr. Delbert Doppler, Jim flees, discovering that the sphere contains a holographic star map pointing to the fabled treasure.
Enthralled by the possibility of adventure, Doppler commissions the ship RLS Legacy, under the command of the brave feline Captain Amelia and her stone-skinned first mate, Mr. Arrow. The quirky crew is led by the enigmatic cook, John Silver, whose intentions Jim begins to suspect might align with the cyborg Billy warned him about. As the voyage ensues, Jim works in the galley, forming a difficult relationship with Silver while also befriending his shape-shifting pet, Morph.
The ship faces a catastrophic event when they encounter a supernova, which puts Jim’s quick thinking to the test as he secures the crew's lifelines. However, during the chaos, a treacherous arachnid named Scroop severs Mr. Arrow's lifeline, leading to his demise. After narrowly escaping, Jim finds himself unjustly accused by Scroop, but Silver comforts him amidst the unfolding betrayal.
Upon arriving at Treasure Planet, Jim uncovers that Silver is indeed leading a mutinous crew of pirates. Amidst the turmoil, Doppler, Amelia, and Morph abandon ship, prompting Jim to seize the map. In a heart-wrenching moment, Silver cannot bring himself to shoot Jim, allowing him to escape with the others. As the group attempts to sail away, they realize that the map is actually Morph in disguise, leaving the true map still aboard the ship. They encounter B.E.N., an eccentric navigational robot formerly belonging to Flint, who, after recovering his memory circuit, reveals that Flint’s treasure is cursed.
As the pirates pillage the treasure, Jim locates Flint's skeleton clutching the missing circuit. Once reinstated, B.E.N. reveals that Flint had rigged the planet to self-destruct upon the discovery of his loot. In a thrilling escape, Silver chooses to save Jim over his treasure, and the group boards the Legacy, which soon becomes crippled in the chaos. With quick ingenuity, Jim fashions a makeshift sailboard to guide them to safety through a portal leading home, while Doppler navigates the Legacy from behind.
In a poignant goodbye, Jim allows Silver to escape and gifts him Morph alongside a stash of treasure. Back on Montressor, Jim uses his newfound wealth to restore the Benbow Inn, welcoming B.E.N. as a new member of the family. With mentorship from Silver shaping his character, Jim’s journey culminates as he embarks on a promising future as a cadet at the Interstellar Academy, thanks to a recommendation from Amelia.
