Alvirah Meehan, the lottery winner turned amateur sleuth, and her husband Willy, private detective Regan Reilly, her new husband Jack, and Regan's parents are all guests on the Royal Mermaid's maiden voyage, the Santa Cruise. The ship's passengers include members of the Oklahoma Readers and Writers group - who are planning a mystery seminar dedicated to a Ghost of Honour, the late Left Hook Louie - as well as assorted other charitable folk all planning on a restful post-Christmas vacation. What the guests don't know is that two escaping criminals have been smuggled on board. The hoped-for tranquility quickly vanishes when a terrified mystery fan swears she has spotted the Ghost of Honour in the ship's chapel, and soon after - while a storm develops outside - an attempt is made on the life of a feeble passenger. As the Royal Mermaid sails on through troubled waters, Alvirah, Regan and Jack are uncovering clues that lead them to dangerous criminals.