I thought the book was great. I love all of Colleen Coble's books!
A woman and a small child are discovered by the roadside. The woman has amnesia, which prevents her from remembering who she is or even who the child is. However, it soon becomes apparent that she's one of the targets of a "missionary killer", that is, a serial killer who specifically targets people who he believes have sinned.
Coble's characters are somewhat realistic, if a little simplistic at times. The plot is very well fleshed out, and there's a lot of detail regarding the lives of Michiganders in the Upper Peninsula (I almost wished she'd include the Greek recipes she describes) as well as the sport of geocaching to be found. Her research is top-notch.
A couple of the characters featured in this novel, Bree and Kade, are also featured in the author's Rock Harbor series.