Martha's Vineyard, 1929. Prohibition is in full swing, and Emily, a Midwest transplant, has never met her wealthy Aunt Isabel. That is until, after her mother's death, the courts declare Isabel her guardian. Their first meeting is a disaster. Emily's clumsy curtsy earns her only a frosty glare, and she quickly realizes she's in for a crash course in East Coast high society. But manners take a back seat to mystery when Isabel's dear friend, an accomplished sailor, vanishes at sea. Convinced it's murder, Isabel recruits her niece to catch the killer, pointing the finger at two dangerous men: a ruthless Mob boss and the fastest rumrunner in the harbor. While Emily crosses paths with gangsters on the island, she may just find home on its miles of coastline and among its quirky inhabitants-her stoic Aunt Isabel included.