To Dwell In Darkness by Deborah Crombie

Things have changed in the Kincaid household.  Duncan Kincaid has returned to the job as a detective superintendent after a lengthy paternity leave.  He is, without warning, demoted and transferred from his job heading up an investigative team at Scotland Yard to the London Borough of Camden, where he has a totally new murder team and new bosses.  He retains his title, but can't understand why the change has been made and his old boss isn't around to ask.  His wife, Chief Inspector Gemma James, has been promoted and also heads up an investigative team in another station.

But policeman rarely have time to ponder.  Kincaid and his team are called to historic St. Pancras train station.  A music festival there is interrupted when a protest group against modernization sets off a phosphorus grenade, killing the holder.  The group, mostly young university students and the homeless young, insist that they were setting off a smoke bomb only.  If that is true, how did the grenade come into their possession and who would want to kill one of them?  Even more suspicious, one of the group has disappeared and no one has any idea where he might be, or even who he really was.  Did he substitute the deadly device?

Gemma has her own murder to worry about.  A teenage girl has been lured to a deserted spot, kidnapped and killed.  Gemma and her team are sure they know who did it, but have no way to prove it.  Can they discover the evidence they are sure must exist somewhere?

This is the sixteenth novel in Deborah Crombie's series in this interesting mix of murder and the domestic lives of a young professional couple in London.  The Kincaid household consists of a teenager, a young son, and a foster child of three, along with lots of family connections and friends.  The couple must balance the demands of a two career household with those of the children, and it is interesting to see how this common dilemma plays out in the law enforcement area.  This book is recommended for mystery readers.  Although part of a series, it can also be read as a stand alone mystery.  Deborah Crombie is an American, but she always felt she belonged in Britain, and moved there as soon as she could as an adult.  Readers will agree she gets the feel of Britain correct, and will enjoy her unraveling of the mysteries surrounding the couples.