With her son grown, single mum Pearl pursues her lifelong dream and starts a private detective agency, which she runs from her family seafood restaurant in Whitstable. Drawn by her caring but no-nonsense nature, residents flock to her with all kinds of cases but when she discovers her friend and oyster supplier dead, DCI Mike McGuire arrives from London to lead the murder investigation. Gruff and aloof, Mike initially clashes with Pearl, but they soon find themselves working together.