Delphine Lecompte has devoted her journalistic career to exposing secrets, but there's one mystery she's never been able to crack. After her mother's assassination when Delphine was eight, the police were unable to locate her father. They found no photographs of him, no paperwork in his name, no record that he ever existed. An anonymous donor paid for Delphine to attend an elite boarding school. When she broke into the school office to find her records, Delphine discovered the tuition cheques were being sent from Paris. The address eventually led her to the Palais de l'Institut.

Inside the palace, five councils operate in utmost secrecy. Though outwardly they promote the expression and innovation of French culture, their covert occult activities exert more influence on the world than anyone suspects. The oldest council is L'Académie Française. Composed of forty members of the literary community who call themselves "Immortals", the Academy oversees the purity and correct usage of the French language-though their true purpose is far more sinister.

When a member of the Academy vanishes under mysterious circumstances, Delphine recognises his photograph as the newspaper comes off the press-it's her father, who she hasn't seen in nearly twenty years. She reluctantly teams up with her ex-fiancé, a Flemish scholar who has his own urgent reasons for investigating the French Academy. Together they work to find the truth about Delphine's father and the society he was part of, immersing themselves in a world of deadly secrets as they uncover a conspiracy going back centuries to the founding of L'Académie Française.