What is the theme in Chasing the Dime: A Novel by Michael Connelly?

A colloquial sounding theme would be from hero to zero and back. When Henry first gets Lilly's number, the similarities to his sister Isabella are so great that he is unable to let it rest. He has to discover what happened to Lilly and to help her if he can. He is compelled to do this because he was unable to do it for his sister. When, as a child, when his stepfather had him going into buildings and looking for her, he had actually found her once. She had begged him not to make her go home. She told him that their stepfather had been raping her for some time and that even living in flop houses with junkies was a preferable environment to her. He had wanted to help her then.