Six months have passed since the first murder investigation Detective Reed Mattox and his K-9 partner worked together, finding them in the throes of a steamy Midwestern summer.
Working in The Bottoms, a notorious neighborhood on the west side of Columbus, they expect the usual increase in low-level crime the hottest months tend to bring but nothing compared to this.
A body is found, and then another, and soon Reed and Billie are on the trail of a potential serial killer whose only pattern for his crimes seems to be no pattern at all.
Bodies begin piling up at an alarming rate. Battling against the heat and the clock, they must sort through the crimes to identify a common thread that ties them all together. If they can, they may be able to stop the murders.