As the thick smoke shrouds Chimney Town, the whispers about obscured stars, once dismissed by the townsfolk, echo in the background. On a fateful Halloween Day, an unexpected entity emerges from the nearby landfill—an unusual being born from refuse, it possesses a budding consciousness. This peculiar creature captures the attention of Lubichi, son of Bruno, who is desperate for help. In a twist of fate, Lubichi seeks refuge with the Inquisitors, only to find himself escaping from the very authority he hoped would protect him.
As the journey unfolds, Lubichi crosses paths with a loquacious thief named Scoop. In exchange for a pact of silence, they agree to three cherished wishes, with their first goal being an escape from the oppressive smoke that engulfs their city. Their daring escape is marked by a powerful explosion, propelling them towards newfound freedom as they embark on their quest.
Reflecting on the past, Lubichi fondly remembers the bracelet crafted by Bruno, a token filled with wisdom about the mysteries of smoke—a piece of jewelry that would become essential on his journey toward truth and self-discovery.
As Lubichi's quest for Poupelle (the being from the landfill) begins, he finds himself in a constant struggle between his desire to safeguard his new friend and the burdens of his mundane existence as a chimney sweep. He cleverly disguises Poupelle and introduces him to the smoke-choked world of chimney climbing. As they navigate this unfamiliar and dangerous terrain, Poupelle's innocent curiosity sparks a series of revelations, pushing Lubichi to confront the harsh truths that lay hidden beneath the thick, gray smoke.
In a fortuitous turn of events, Poupelle becomes entangled with a group of children who share tales of Lubichi, including the tragic story of Bruno, who met his demise at the hands of monstrous creatures after leaping from the infamous Forbidden Cliff. Haunted by this narrative, Poupelle realizes he has inherited Bruno's reputable tailoring business. In a whimsical twist, he shares one of Lubichi's dreams with the children, prompting uncontrollable laughter.
However, the light-hearted atmosphere is soon replaced by tension. A confrontation with Antonio, one of the children, leads to Poupelle accidentally falling into a nearby lake. Later, while Lubichi adjusts his attire at the tailor shop, he receives a caution from Mr. Sue about the dangers of heresy that lurk in their city, a stark reminder of the delicate balance that must be maintained.
As Lubichi delves into his memories, he remembers his childhood experiences and the gentle guidance of his father. Recollections of a lost hat atop a rooftop and a swift fall—mercifully broken by Bruno's intervention—flood his mind. The weight of reality returns when he arrives home, finding Inquisitors interrogating his mother, whose desperate plea for him to obey the law weighs heavily on Lubichi, who fears he may lose another loved one.
As the Inquisitors depart, an ominous aura lingers in the air. Dan, a local, suffers a terrible fall, leaving him severely injured and almost apprehended by the authorities before being rushed to a hospital. In the wake of this chaos, Antonio encounters Lubichi, still grappling with the truth about Bruno's tragic end. A confrontation ignites, with Antonio directing blame at Poupelle for a recent surge of asthma cases in the town.
Upon visiting Poupelle's tailor shop, Antonio engages the enigmatic being in a heated exchange, causing Poupelle to drop his defenses and showcase a vulnerability that had remained hidden. When Poupelle returns to Lubichi's modest home, he shares his adventures and reveals that the foul smell in the air is merely a result of his quest to discover the mystery behind Bruno's cherished bracelet, which accidentally resides within Poupelle himself.
A towering sunken ship suddenly catches Lubichi’s eye, leading to the realization that his father’s fantastical stories were based in reality. In a moment of unwavering loyalty, Lubichi turns to Scoop, imploring for the smokeless explosives he had used to breach the city’s barriers. As Scoop attempts to deliver, he uncovers a profound truth: Lubichi is Bruno’s son, a revelation that revives memories of the city’s tumultuous history.
Legend has it that Silvio Letter, an economist from over 250 years ago, endeavored to bring order to the chaos driven by rampant capitalism. His innovative solution was the creation of “L,” a unique decaying currency designed to foster harmony, which inevitably clashed with the powers of the Central Bank, leading to his arrest and a return to chaos.
Fueled by this newfound understanding, Lubichi and his companions begin constructing a bomb on the sunken ship. However, their clandestine operation is interrupted by the Inquisitors who draw near. In a bold gesture, Scoop, motivated by loyalty, captivates the authorities with an impromptu speech, diverting their attention and giving Lubichi a moment to escape.
As Antonio and others launch the ship into the sky amidst turbulent weather, Lubichi's hat and Poupelle's coat are swept away. But undeterred, Lubichi detonates the bomb, igniting a brilliant explosion that unveils the starry sky for all to witness.
When the smoke clears, the citizens of Chimney Town, rejuvenated by the sight of the starry expanse, decide to abandon their smoke production, allowing their city’s true beauty to finally shine. As Poupelle returns Lubichi’s hat and embarks on a journey of his own, releasing his essence into the universe, Lubichi is left to contemplate the profound impact of this transformative moment in their city’s legacy.
