"Spy×Family" is set in a fictional world resembling Cold War-era Europe, where tensions between the nations of Westalis and Ostania are high. The story centers on Twilight, a highly skilled spy from Westalis tasked with a critical mission: to infiltrate Ostania's elite social circles and gather intelligence on Donovan Desmond, a key political figure threatening peace. To achieve this, Twilight must create a fake family to enroll his "child" in Eden Academy, a prestigious school attended by Desmond's son.

Twilight adopts Anya, a young girl with telepathic abilities, who was previously an orphan subjected to experiments. Anya is eager to help Twilight, as she dreams of having a loving family. Twilight also recruits Yor Briar, a seemingly unassuming office worker who secretly works as an assassin. Yor agrees to the arrangement to maintain her cover and protect her brother, who works for the government. Together, the three form a makeshift family, each hiding their true identities from one another.

The narrative explores the dynamics of this unconventional family as they navigate their daily lives while balancing their secret professions. Anya, aware of her parents' true natures through her telepathy, often finds herself in humorous and heartwarming situations as she tries to keep the family together and help Twilight complete his mission. Yor, despite her deadly skills, is kind-hearted and struggles with domestic tasks, adding a layer of comedy to the story. Twilight, though initially focused solely on his mission, gradually develops genuine affection for his new family.

The series blends espionage, comedy, and slice-of-life elements, with the family's interactions forming the emotional core of the story. Key plot points include Anya's attempts to excel at Eden Academy to get closer to Desmond's son, Yor's efforts to balance her dual life, and Twilight's growing internal conflict between his duty as a spy and his attachment to his family. The story also delves into the broader political tensions between Westalis and Ostania, with the family's actions occasionally influencing the larger geopolitical landscape.

"Spy×Family" balances its lighthearted moments with underlying themes of trust, identity, and the meaning of family, creating a narrative that appeals to a wide audience. The characters' hidden lives and the constant threat of exposure add tension, while their genuine care for one another provides emotional depth. The series successfully combines action, humor, and heartfelt moments, making it a standout in its genre.