Those hilarious southern sisters, who prove that sibling rivalry never ends, are heading for a vacation at the beach. Mary Alice's flamboyant behavior aside, serious, sensible Patricia Anne looks forward to relaxing at her sister's beachfront condo in Destin, Florida, so she kisses her ever-loving spouse Fred goodbye, reminds him to water the plants and feed the dog, and the girls head south for some fun in the sun.

Mary Alice loses no time in making the acquaintance of just about everyone in sight, so watching the sun go down on the beautiful shores of the Gulf of Mexico is a welcome respite as far as Patricia Anne is concerned … until a dead body washes up in the waves and the victim turns out to be one of Mary Alice's newfound friends. With no witnesses to the crime except a few great blue herons, the sisters have no choice but to bypass the clueless police and follow their own instinct to find the killer. Before long they're on a murky trail of dirty real-estate deals, giant turtle habitats, and a sea of evidence pointing to a mammoth motive for murder.