Linus Baker is a quiet, middle-aged caseworker living a mundane and structured life in a rainy city. He works for the Department in Charge of Magical Youth (DICOMY), an impersonal bureaucracy that oversees orphanages for magical children. Linus is meticulous in his job, always adhering strictly to the rules outlined in the extensive handbook that governs his work. His life is defined by routine—long days at the office, lonely evenings at home with his cat Calliope, and interactions with coworkers who barely notice him. He has never considered breaking the rules or questioning the system he serves. That all changes when he is unexpectedly summoned by Extremely Upper Management for a classified assignment.

Linus is given a special case: he must travel to Marsyas Island, a remote and mysterious location, to assess the viability of an orphanage that houses some of the most unique and potentially dangerous magical children in existence. Unlike the facilities he usually inspects, this orphanage is home to only six children, each with abilities that challenge the limits of what DICOMY considers acceptable. More unusually, the orphanage is run by Arthur Parnassus, a man whose methods and motivations are shrouded in secrecy. Linus is given a month to determine whether the orphanage should remain open or if the children should be relocated.

When Linus arrives at Marsyas Island, he is immediately out of his depth. The house in the cerulean sea is unlike any institution he has visited before—vibrant, warm, and filled with an undeniable sense of belonging. The children, each feared by the outside world, are both wonderful and terrifying. Talia, a gnome, is fiercely protective of her garden and enjoys plotting people’s untimely ends in jest. Phee, a young forest sprite, has a deep connection to nature and is fiercely independent. Theodore, a wyvern, is curious and mischievous, hoarding shiny objects. Chauncey, an amorphous being, dreams of becoming a bellhop and is obsessed with good manners. Sal, a traumatized shapeshifter, struggles with trust but finds solace in writing. And then there is Lucy—short for Lucifer—the six-year-old Antichrist, who has a penchant for dramatic flair and dark humor but is, at his core, just a child yearning for love and acceptance.

At the heart of the orphanage is Arthur Parnassus, a man whose unwavering devotion to the children is unlike anything Linus has seen before. Arthur is warm, kind, and fiercely protective of his charges, willing to defy the world to ensure their safety and happiness. Despite Linus’s initial reservations, he finds himself drawn to Arthur’s compassion and unconventional approach to care. As the days pass, Linus begins to question everything he has believed about magical children, the role of DICOMY, and his own life. The more time he spends on the island, the more he realizes that the real danger lies not in the children but in a society that fears them simply because they are different.

As Linus’s month-long assignment nears its end, he is faced with an impossible choice. Does he follow the rules, condemning the orphanage to an uncertain fate? Or does he take a stand, risking his career and the life he has known for the sake of love and family? The answer becomes clear when DICOMY sends an official inspection, led by those who view the children as little more than threats to be contained. Linus, no longer the man who left the city a month ago, refuses to let them be taken away. With Arthur’s unwavering belief in him and the children’s trust, Linus finds the courage to defy the system, proving that love, acceptance, and found family are more powerful than fear.

In the end, Linus chooses Marsyas Island. He resigns from DICOMY, returning to the place that has become his true home. Arthur and Linus, once strangers, now stand side by side, guardians of a family that exists outside the boundaries of society’s expectations. The house in the cerulean sea remains a sanctuary, a testament to the idea that everyone deserves love, no matter how different they may be.

The House in the Cerulean Sea is a tender, heartwarming novel that celebrates found family, acceptance, and the courage to challenge the status quo. With its whimsical charm and deeply emotional core, TJ Klune’s story reminds readers that sometimes, the most extraordinary magic lies in kindness and belonging.