She’s only just moved to a new city with her mother, her big sister, and her little brother, but right away Agatha Christine sets up a new office in the basement. As far as the ten-year-old A.C. is concerned, she’s a bona fide private detective. Her specialty is theft and surveillance. What she doesn’t have is any friends – there’s just no space for that in the life of a busy gumshoe. Or maybe there is. Whenever the neighbour boy Vincent crosses her path, A.C. feels a little queasy. Something is not right, that much is clear. Then she actually gets a job – the local kiosk is regularly plagued by shoplifting. Is Vincent involved? How can A.C. keep her mother, with her matchmaking attempts, off her back? And what’s going on in the old factory? In this lovingly animated whodunit, the sharp-witted loner has to solve what is probably her biggest case.