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, dealing with the usual increase in low-level crime that the hottest months tend to bring, when something unexpected happens.
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.
Battling against the heat and the clock, the K-9 team 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.
If they can't, there's no telling how many more people will become victims before the dog days of summer end....