Downpour is the sixth book in the Greywalker series, and Richardson has indeed allowed Harper Blaine to chase after lesser monsters for a time. This is a good thing, as after she was shot at the end of the last book, she's lost stamina, and a certain amount of her Grey manipulating abilities, though perhaps has gained some more subtle arcane skills. The saga continues to be a little dark, but as one might expect from a setting in the western rain forest zone, gets pretty wet, as well.
While investigating a witness for a lawyer friend in a mundane case, Harper encounters the ghost of a man who has been murdered and his car disposed of by dumping it in the middle of Lake Crescent, near Port Angeles. For better or worse, Harper is still the chosen agent of the Guardian Beast of the Grey, and it's up to her to remedy disturbances in that realm.
The lake area has long been a center and source of magical power, and two major ley lines cross there. But one of the ley lines has come unglued when its anchor was removed, and the resulting flailing around of the untethered end has resulted in a free for all situation for the magic users, magic creatures, and other denizens of this sleepy little resort area.
Richardson weaves a lot of local flavor into this tale, and spent a significant amount of time in the area researching its history. Harper and Quinton take their relationship to a whole new level, which may foreshadow a more active role for him in future installments. In place of the Egyptian mythos that we saw in Labyrinth, she adds an element of Chinese mysticism to this story. Will she continue to have Harper roam farther and farther afield, or will we return to her old stomping grounds in the next novel?