Despite her father's wishes for her to lead a dull life, Mabel West, daughter of well-known mystery novelist Raymond West, yearns for excitement as a detective. Against his wishes, she rebels and travels to London to become the trusted assistant of Hercule Poirot. With Raymond's reluctant approval, she sets off on a thrilling adventure of solving mysteries and engaging in suspenseful escapades. Yet, he also requires her to spend some quality time with her great-aunt, Jane Marple, in the charming village of St. Mary Mead.