Nowadays, in a France where the monarchy has never been abolished, a plane crash costs the life of the entire royal family. Samia, a naive teacher without authority, learns that her son Cédric, a simpleton teenager born of a temporary union with a nobleman, is the heir to the throne. Now named Louis 28, Cédric has many projects for the kingdom such as "the abolition of math", but he will come up against the directives of a retrograde regent and ready to do anything to trip him up. Mother and son are thus propelled into a courtyard where these "toothless" are the object of all treachery.

Astrid Nielsen works in the library of the judicial police. She has Asperger's syndrome. With an incredible memory, she excels at analyzing files of ongoing investigations. The district commander decides to use it to the fullest, entrusting her with very complex investigations which have remained unsolved to date.