Follows the insatiably curious young reporter Tintin and his fiercely loyal dog, Snowy, as they stumble upon a model ship that conceals an explosive secret. Engulfed in a centuries-old mystery, Tintin becomes the target of the nefarious Ivan Ivanovitch Sakharine, a villain who believes Tintin has stolen a priceless treasure linked to the notorious pirate Red Rackham. Together with Snowy, the gruff yet lovable Captain Haddock Andy Serkis, and the bumbling detectives Thompson & Thomson, Tintin embarks on a thrilling quest across the globe to locate the long-lost shipwreck of The Unicorn. This wreck may hold the key to untold wealth—and a haunting curse.
Set in Belgium in 1955, the adventure kicks off at a bustling town square where Tintin, after having a caricature drawn by local artist Georges Prosper Remi, spots a miniature pirate ship named "The Unicorn" for sale. Captivated by its charm, he makes the purchase for a mere pound, only to attract unwanted attention. A large man with a mustache, speaking in an American accent, offers to buy the ship for double the price, warning Tintin to escape danger. Moments later, a slender man in a red coat also attempts to procure the ship, revealing its origins from Marlinspike Hall but ultimately leaving without it—and leaving Tintin puzzled about his sudden popularity.
Once home, Tintin's curiosity gets the better of him. As he inspects his new treasure with a magnifying glass, his pet dog Snowy chases a feline intruder, accidentally breaking the ship. Amid this chaos, a small metal cylinder slips from the wreckage and rolls unnoticed under the table. Seeking out answers, Tintin heads to the maritime museum's library, where he discovers that the ship was rumored to be carrying secret cargo—perhaps linked to the legendary Captain Sir Francis Haddock, who believed his bloodline was cursed after the ship sank.
Upon returning home, Tintin is horrified to find the model ship missing. Convinced that the mysterious thin man has stolen it, he sneaks into Marlinspike Hall to confront him. Inside, he finds an identical ship in a glass case but is soon knocked out. When he awakens, he meets the thin man, who reveals himself as Sakharine, and learns that though they share the same ship name, his is intact while Tintin’s is shattered.
Upon returning to his apartment, Tintin discovers it ransacked. However, he triumphantly finds the metal cylinder, which contains a cryptic scroll pointing to a deeper mystery. Just then, he overhears an altercation below; an American man pleading for help is shot right before Tintin's eyes, sending him into the chase of his life. With the police detectives, Thompson and Thomson, befuddled but determined, Tintin becomes embroiled in a thrilling series of events that leads to his abduction by several large men.
With Snowy at his side, Tintin finds himself aboard a grim cargo ship called the Karaboudjan, where he meets a drunken but strong-willed Captain Haddock [Andy Serkis]. Upon realizing their connection, they make a plan to escape, but their journey takes a wild turn when they find themselves in a crash landing in the desert after narrowly escaping Sakharine's clutches.
As the eyelids of a storm close in on them, Haddock experiences vivid flashbacks of his ancestor’s tale—a story steeped in betrayal and adventure. This ancestral legacy becomes crucial as they navigate perils toward their ultimate goal: the treasure of Red Rackham.
Their escapades twist across cities and perilous landscapes, eventually culminating in a high-octane chase, a confrontation with Sakharine, and an explosive revelation that takes them back to Marlinspike Hall, where the secrets of the Unicorn and Rackham intertwine. Encounters with diverse characters, including a renowned opera singer, and thrilling twists lead to a final confrontation amidst clashing swords and suspenseful moments.
As dawn breaks over their journey, Tintin and Haddock clean up the final threads of their adventures. The scrolls reveal coordinates, pointing them toward hidden treasures, setting the stage for yet another page in their legendary saga—a journey towards the elusive secrets of Red Rackham's treasure awaits them, igniting their spirits for the next grand adventure.
