It's 1926. The West Coast Development Company is staging its biggest land deal in Homosassa, Florida, selling pieces of a planned city to speculators who dream of a tropical paradise. Army nurse Cornelia Pettijohn takes leave to travel to Florida with her ancient uncle, who claims that he wants a warm winter home. When their car breaks down, they take the local train, The Mullet Express, into Homosassa. By the time they arrive, though, a passenger has been poisoned. A second murder victim boards the train later, iced down with the fish. Uncle Percival's hidden agenda makes him the sheriff's prime suspect. Cornelia and Teddy Lawless, a twenty-year-old flapper in a body pushing sixty, must chase mobsters and corner suspects to dig her uncle out of the hole he's dug for himself.