This is the third novel by author Karin Slaughter that features the characters of Will Trent and Faith Mitchell - both work for the Georgia Bureau of Investigation. They have connected with Sara Linton, a trauma doctor who was previously married to cop Jeffery Tolliver in the Grant County series. The two prior books, Triptych and Fractured, introduced the interesting duo of Will and Faith (he with severe dyslexia and she with a hard life past) and they met Sara when she returned to Atlanta to work in a hospital there. The complex characters have interesting and unique relationships to each other and this provides a great deal of depth to the narrative.
I really enjoyed this book and highly recommend it to anyone looking for a good suspense thriller. I do think it would be best if the reader started at the beginning of the Grant County series with Blindsighted (Dr. Sara Linton) and worked his/her way up to this one in order to fully see the changes and growth that have transpired in the characters, but I do suppose it could be enjoyed as a stand alone as well.