Husband and Wives — Susan Rogers Cooper

When Mary Hudson is discovered on her kitchen floor, bludgeoned to death with a meat tenderizer, Sheriff Milt Kovak of Prophesy County, Oklahoma, and his psychiatrist wife Dr Jean McDonnell are drawn into a murder investigation that is as intriguing as it is chilling. It soon emerges that Mary's husband, Jerry, is a polygamist, and the family belong to a church called the New Saints Tabernacle. As Milt and Jean delve deeper into the church and its customs, they soon become embroiled in a murky and mysterious world.