Jennie goes on vacation to Ireland with her grandmother who wants to settle an estate. However, Jennie is threatened, and her grandmother is asked to investigate a mysterious death which had occurred fifty-five years ago.

Teased for his youth and diminutive stature, twelve-year-old Fletcher Moon is a fully-licensed detective who, while investigating his first case, is framed for arson and must team up with his prime suspect to clear his name and find the real criminal.