When the Snow Melts

The story begins with Outline of Murder. It continues with When the Snow Melts.

Although retired from the force, when Brad Schrader’s best friend, Joe Harms’ wife is
missing, he helps the local sheriff with the investigation.
By chance, Brad discovers Valerie Harms’ dead body, and in an attempt to get him off
the case, the killer kidnaps Brad’s five year old son, Adam, turning the case personal.