Ten-year old Agathe-Christine, or simply AC, fancy mysteries and from the basement in the building, where she has just moved in, she has established a small detective bureau.

Ten-year old Agathe-Christine, or simply AC, prefers to be on her own. AC fancy mysteries, and from the basement in the building, where she has just moved in, she has established a small detective bureau. AC's first mystery appears to be simple to solve, but before long AC finds herself involved in a much more complicated affair, than she could have ever foreseen.

Agatha Christine, aka AC, is ten years old. She really wants to be a private detective and has her own office in the family basement. She doesn't care that people think she is weird. One day she meets a boy in the local shop. His name is Vincent and he is beautiful and mysterious. A loner, just like her. AC gets a weird feeling in her stomach every time she sees him, and she takes it as a warning. There is something suspicious about that boy. She ditches all other investigations and devotes her full energy to surveilling Vincent.