Faithless by Karin Slaughter

 When Sara Linton and Jeffrey Tolliver go for a walk in the woods around Sara's parents' house, they don't expect it to end in horror.  But it does.  Jeffrey tripped over something and they realize it is a pipe.  The pipe leads to a coffin buried in the earth and a young girl who has been buried alive and is now dead.  

The two are used to seeing dead bodies.  Jeffrey is the police chief in this small Southern town and Sara the coroner.  But this is a particularly gruesome death.  Who is this girl?  Who hated her enough to do this?  As the investigation progresses, it turns out that the girl did not suffocate.  Instead someone sent cyanide down the pipe and poisoned her.  She is part of a religious family that runs a large farm that grows soy and employs ex-cons and drifters.  Did one of them do this?  Was it part of the family?  The family sends off cult vibes and Jeffrey isn't sure what they would do.  Can the two find the answer before more girls are killed?

This is the fifth of the six novels in the Grant County series.  The crime is arresting and the investigation is interesting.  Jeffrey and Sara are in an on again, off again relationship, moving through marriage, estrangement and reengagement.  A secondary character, Lena, is a detective in the force who faces many issues from her own past and she is featured again in this novel.  Readers will be caught up in the action and horror that only Karin Slaughter can deliver.  This book is recommended for mystery readers.