The Castle in the Sea

The original work, The Castle in the Sea, was published in 1983 by Houghton Mifflin. (See top cover artwork.) 

The paperback edition was published by Fawcett Juniper. (See bottom cover artwork.)

Synopsis

Beautiful, intelligent, and an heiress to wealth beyond imagining, Lucinda knows that the world judges her to be the most fortunate of young women. But in this sequel to The Spanish Smile, Lucinda is afraid. She is now the ruler of the fabled Isla del Oro and free from the cruel power of her mad father. Yet Lucinda, although surrounded by admirers and servants, senses that she is as much a captive in the great stone castle as she had been while her father lived. When her fiance, a Spanish nobleman, comes to the castle, bringing his imperious mother, Lucinda hopes that she has found someone who might help her escape from her gilded prison. But instead of escape, she finds her sense of peril deepening. Now her life--and her fiance's life as well--are threatened by mysterious "accidents."