The Crossing Places - Elly Griffiths

An atmospheric adventure with beloved forensic archaeologist and "captivating amateur sleuth" Ruth Galloway, as she teams up with Detective Chief Inspector Harry Nelson to investigate a set of remains, thought to be the bones of a little girl who went missing ten years before"an inspired creation" (Louise Penny).
Forensic archeologist Ruth Galloway is in her late thirties. She lives happily alone with her cats in a remote area near Norfolk, land that was sacred to its Iron Age inhabitantsnot quite earth, not quite sea. But her routine is harshly upended when a child's bones are found on a desolate beach. Detective Chief Inspector Nelson calls Ruth for help, believing the bones to be the remains of Lucy Downey, a little girl who went missing a decade ago and whose abductor taunts him with bizarre letters referencing ritual sacrifice, Shakespeare, and the Bible. Then a second girl goes missing and Nelson receives a new letterexactly like the ones about Lucy. Is it the same killer? Or a copycat murderer, linked in some way to the site near Ruth's remote home?