It's 1988 in England, and Florence has decided to retire from her longtime nursing career. Fancying herself a modern-day Sherlock Holmes, she takes a job as assistant in a one-man private investigator's office. Tired of answering the phone and filing, she's desperate to solve a real case. The opportunity finally arrives when her friend Andrea suspects her husband, Geoffrey, is having an affair. Florence tries mightily to get to the bottom of Geoffrey's strange behavior and disappearing acts, even involving her reluctant boss, but comes up empty. However, Geoffrey's secret is revealed to Andrea following a shocking event that changes both their lives forever. Hidden is equal parts cosy mystery and domestic drama, and explores the secrets we keep from others-and ourselves-and how much we allow others to see, even those closest to us.