What is the theme in The Key to Midnight by Dean Koontz?

Manipulation is a main theme in the book. Joanna Rand believes she is the daughter of kind, considerate parents, who raised her to have a sense of individuality. In reality, Joanna Rand is not even Joanna Rand. Robert and Elizabeth Rand are a figment of someone's imagination. Joanna's mind has been tampered with, her memories erased, and new ones implanted. Joanna is really Lisa Chelgrin, the daughter of an American senator. She was kidnapped and given a new life in order to make her forget something dangerous to her, to her father, and to the people who control her father. However, Joanna is beginning to remember the past through nightmares and panic attacks that have begun to affect the way she functions in everyday life.