Laura Palmer left her Boston home to travel west to San Juan Capistrano to take a position as a tutor for the three young children of Ian Castle, a widowed walnut grower. She also plans to take advantage of the health benefits of the local mineral hot springs. Upon arrival, Laura is immediately aware that something is amiss, and there is definitely friction between Ian and his son, Reuben. Laura believes that Reuben is not as troubled as his father seems to think and is determined to prove it. She also discovers that the two younger sisters, Cassie and Bridget, display certain talents that may not be recognized by their father.

Ian's mother, Fiona, lives in a cottage on the estate and provides Laura with answers to some of her questions, but there always seem to be more questions. Then, Laura meets Dylan, a handsome vaquero from a nearby ranchero. She is both attracted to him and wary of him but finally comes to trust him after learning he is an undercover Pinkerton agent and enlists his help to get to the bottom of the secrets surrounding Walnut Hill.