In order to maintain the state of peace between the rival nations of Westalis and Ostania, a Westalis agent codenamed "Twilight" is tasked with spying on Donovan Desmond, the leader of an extremist political party within Ostania. However, due to Desmond being notoriously reclusive, the only way Twilight can get close to him is to enroll a child in the same private school as Desmond's son and pose as their father. To accomplish this, he creates the alias of Loid Forger, adopts a young orphan girl named Anya, and marries a woman named Yor Briar, to create the image of a happy family. However, Yor is in fact a professional assassin, with neither her nor Loid being aware of each other's true identities. Both of them are also unaware that Anya can read minds, and knows their true professions. Despite these unknown factors, Loid must learn to play the role of the perfect father and husband in order to carry out his mission.
