McDermid likes to slow-cook her stories. She stirs the pot and adds a variety of ingredients as the plot thickens and the story progresses. She takes her time to cultivate it, which is definitely her particular style.
Karen is still grieving for her lover and partner, and that grief is what leads her to the sub-plot aka an important political hot topic of our era, refugees. The author weaves it into the main plot with the greatest of ease.
Karen has got a whiff of a connection leading from a suspicious death to an old cold case. There is just something dodgy about two deaths in the same family but decades apart.
Simultaneously the chance DNA extraction has brought back a hit in the database in an old murder case. So on the one hand she has her hands full with her own case, but she can’t resist meddling with cases outside of her unit. Not exactly the right thing to do if the head honchos want rid of you.
I guess in a way she is delving into as many ventures and mysteries as she can to stop from obsessing about Phil. A coping-mechanism if you will.
McDermid describes the police and judiciary systems of Scotland very well, although it does seem quite antiquated. Then again it might just be the unnecessary bureaucracy of said systems. Of course the flip-side of the coin is the fact there are rules and laws in place for a reason.
Hopefully this won’t be the last we see of Karen and her trusty sidekick The Mint.