What is the theme in Deal Breaker by Harlan Coben?

Deceptive appearances are a theme in the story. Not all of the characters in Deal Breaker are who or what they appear to be. For instance, Esperanza Diaz, Myron Bolitar's secretary, was at one time a professional wrestler. The fact that Esperanza is also studying to be a lawyer adds a bit of humor to this fact. However, there are other characters in the narrative whose hidden personalities prove to be quite deadly. For instance, Christian Steele is, for all intents and purposes, an intelligent, well-behaved young man who just happens to be a star athlete