Taking Pity is book 4 in the Aector McAvoy series set in Hull.  This follows Sorrow Bound, in which things end in a pretty dark place for Aector and his family, who mean everything to him.  In Taking Pity Aector’s boss is taking every measure she can to keep Aector’s wife and daughter safe even if it means he can’t see them or know where they are.  On orders, she distracts Aector by having him look into an old case that never went to trial, the perpetrator has been held for 50 years under the Mental Health Act instead.  The events and characters  from Sorrow Bound with some new additions continue to roll forward in a menacing death march through this book as Pharoah works to hold onto her job and her ethics while keeping people she cares about alive.

This was really well written, with mounting tension throughout the book.  I think it is one of the best in the series so far.  I do think you need to read the series in order to appreciate it.