What is the theme in Mind Prey by John Sandford?

Greed is another theme in the book. John Mail is released from the psychiatric hospital where he was sent after his conviction in several arson cases. Mail focuses on the future by killing a fellow patient for both his life insurance and his name. Mail wants to start over, to disappear and become someone else. Mail's only interest in life is computer games and role playing games. However, when Mail begins getting phone calls from an unidentified woman who once again plants the memory of Andi Manette in his mind, Mail becomes obsessed with possessing Manette and getting back at her for sending him to the psychiatric hospital.