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.
Despite the pharaoh Sesostris's determation, despite the combined efforts of his generals who are searching, in vain, for the culprit, despite daily prayers and the devoted care of the queen and the seven priestesses of the goddess Hathor, the beautiful acacia tree of Abydos is dying.
But the most mysterious of the priestesses, the one who haunts the nights of young Iker the scribe, has an idea: to save the 'Tree of Life', a new pyramid must be built at Dachur, dedicated to Osiris. Sesostris agrees, and plans are afoot to begin building. But what Sesostris doesn't know is that a triple conspiracy has been hatched against him. On the one hand, the Herald, the bearded devil who preaches to the desert tribes, has decided to seize power by having the pharaoh murdered. On the other, at the king's court, an ambitious, thieving traitor has only one solution: to get rid of his master. Finally Iker himself, deceived by appearances, believes that the moment has come to settle his scores. The conspirators only have to await their opportunity ...