Poirot's fastidious logic and Marple's quiet certainty don't just survive the anime treatment, they sharpen in it, their personalities the actual architecture of how mysteries get solved. Mabel between them becomes the reader's permission slip to ask the questions they're already asking. The show trusts you to solve it alongside them instead of explaining everything twice.
Mabel West rejects her father's expectations of a quiet, ordinary life. Desperate to become a real detective, she abandons her comfortable home and tracks down Hercule Poirot in London, determined to work as his assistant. The famous Belgian sleuth is skeptical of this eager young woman, but Mabel's persistence wins him over, and he agrees to take her under his wing. Her father Raymond, a mystery writer himself, accepts the arrangement on one condition: Mabel must regularly return to the countryside village of St. Mary Mead to spend time with her elderly great-aunt, Jane Marple. What begins as an obligation becomes an unexpected education. While Poirot teaches Mabel the art of deduction and criminal psychology in the bustling city, Marple shares her own wisdom about human nature and village secrets. Mabel finds herself drawn into cases that range from straightforward theft to elaborate murder plots, each one sharpening her investigative instincts and forcing her to reckon with a darker side of society than she ever imagined.