A small-town supermarket becomes the scene of a baffling murder when a beloved checkout girl vanishes and is later found dead. Agnes Plummett, a retired librarian with a penchant for puzzles, finds herself drawn into the investigation when her friend, the missing checkout girl, is discovered murdered. The local police, led by the well-meaning but overwhelmed Detective Miller, seem to be pursuing a dead end. Agnes, armed with her sharp intellect and an uncanny ability to notice small details, begins her own discreet inquiries, navigating the close-knit community of Oakhaven and its secrets. She must uncover the truth before the killer strikes again, all while maintaining the facade of her quiet, ordinary life.

The premise of a cozy murder mystery set in a supermarket suggests a lighthearted yet intriguing plot, likely focusing on amateur sleuthing and community dynamics. The 'utterly addictive' descriptor implies a fast-paced narrative with engaging characters and a satisfying puzzle. Readers can expect a traditional mystery structure with a focus on deduction and a resolution that brings closure to the community. The series title, 'The Supermarket Mysteries,' indicates a potential for recurring characters and settings, offering a familiar yet fresh backdrop for subsequent investigations.