What are the motifs in Angels Flight: A Novel by Michael Connelly?

Justice is a recurring idea in the story. The black community of Los Angeles wants justice both for its members who have been wronged and for Howard Elias, their hero who has been slain in cold blood. Harry wants to give this to them, not because he is concerned with the possibility of riots, but because he has devoted his entire career to law enforcement and still believes in the system and justice. However, the police department makes it difficult for Harry to do his job. Information is leaked to the press and Harry's ex-partner, Frankie Sheehan, is accused of killing Elias. Harry finally stumbles on the truth, but it is too late for Frankie, who has been killed in Harry's own backyard.