Not having read the 'night passage parker novel', I can only speculate. It could potentially be about redemption. The night passage could symbolize a dark time in the character's life, and the novel could be about their journey towards making amends or finding peace. The parker might be the main character who has made mistakes in the past and is now on a path, this night passage, to set things right. There could be sub - themes of forgiveness, both self - forgiveness and from others, and the growth that comes with facing one's past actions.