Phyllis Sowers has lived in Siam for many years and this background, coupled with a diligent research, has produced a highly readable mystery of seventeenth century French and Siamese court life. Principally its many faceted plot has to do with the discovery of Philippe, son of the Marquis d'Althion and falsely accused of the murder of the son of de Chaumont, ambassador to Siam. On a mission to Bankok, Maurice, a cousin of the young hero Pieree Laverne and in love with Aimee d'Althion, entrusts Pierre to help with the job of finding Philippe and as a cover-up, places the boy in charge of rebellious prince Nakonon his way back to his country with the mission- whose overt aim is good relations and whose covert one- to get a slice of the spice trade. Straight so far? Well, the upshot of the whole thing-and it's all pretty exciting reading- is that the long disappeared Philippe is revealed as the father of Nakon, (by now firm friends with Pierre.) Philippe had gone to Siam, married a princess, and incurred disfavor with an evil faction of Siamese royalty whose uprising is quelled in a climactic ending. Not without its melodramatic overtones, this is nevertheless good history and suspense. Margaret Ayer's East-West pictures increase a bid for the Anna and the King of Siam market.