What are the motifs in Sunset Express: An Elvis Cole Novel by Robert Crais?

Love is a recurring idea in the story. While Elvis is fighting to ensure that the innocent people are proven innocent and the guilty pay for their crimes, Elvis is also falling in love with the woman of his dreams. Lucy Chenier is a lawyer from Baton Rouge whom Elvis met on a previous case. Lucy and Elvis have been seeing each other as often as they can despite their long distances from one another. Lucy comes to Los Angeles during this case and convinces Elvis that he wants her to be at his side for a long time. However, Elvis knows that Lucy has a controlling ex-husband and a child that inhibit her ability to pick up and move. Elvis decides that he must move to be with Lucy.