What is the theme of the book?

I think the theme of the book is that reveange is not the answer to your problem. In the book Teddy kept looking for reveange and that just lead him to more problems. Teddy thought he had solved the mystery killer, but instead he got caught by the police and got in more trouble. When Teddy got the real killer in his car he was about to kill him but he didn't, the killer killed himself because his baby died. From there Teddy learned that reveange is not the answer. Teddy instead of getting reveange by killing someone he should of got only information and gave it to a specialist so that he would get in trouble.