Cold Rain is the 17th book in the Garth Ryland mystery series. Called an exemplary series hero by Publishers Weekly, Ryland lives and works in the small town of Oakalla, Wisconsin ("Lake Woebegone made sinister") where passions run high, scars go deep, and the face of innocence wears a crooked grin.

Ryland's morning starts badly on a cold wet December morning and goes downhill from there, as the word comes out that detective Michael Higgins, Ryland's friend and surrogate son, is missing in action. Helen Shirer is being stalked. When she sees someone lead her horse from her barn, she calls 911 for help. Michael takes Helen's 911 call and then fails to arrive at her house or call in his position. That's when Danny Palmer calls Garth and they go in search of him. When they find Michael's 4Runner upside down in Owl Creek at the foot of Camp Collier, it plunges them into a dark mystery that is as deadly as it is deep.

Who is Helen Shirer's stalker and why is she being stalked? Where was Michael going when he took the call and why did he drive off Owl Creek bridge? Why does Michael's captain, Ross Frazier, threaten and then try to stonewall Ryland? How does a fresh Christmas tree magically appear on the front porch of Michael's widow and why does she now turn to Ryland for comfort after she has spurned him in the past? Why did John White Bear bring a weapon to school to show Helen Shirer, only to then be expelled by his principal? And who is trying to do Ryland great bodily harm, and why? These are only a few of the questions that he must answer if he is ever to get to the truth of Michael's death. To further complicate matters, two of his most able allies, Danny Palmer and Ruth, Ryland's housekeeper, are not at their best and have their own demons to slay.

In this, one of his most harrowing journeys to date, Ryland must try to penetrate a heart of darkness that has no seams, only victims. And like the December rain that falls on Michael Higgins' lifeless body, is as pure as it is cold.