Fleeing a humiliating event on the eve of her wedding, Celia Kilbride, a gems and jewellery expert, hopes to escape from public attention by lecturing on a brand-new cruise ship. On board she meets eighty-six-year-old Lady Emily Haywood - the owner of a priceless emerald necklace that she intends to leave to a museum after the cruise. But three days out to sea Lady Emily is found dead - with the necklace missing ... A glamorous cruise on a luxurious ocean liner turns deadly.