Ranger Farrell Donovan lends a member of the Night Vipers' squad to an undercover operation aimed at catching an elusive serial killer. In the blink of an eye, the operation takes an unexpected turn and quickly goes from worse to complete disaster. Blaine, Farrell, and the team are playing catch up all the way to the end. But is there an end? Don't miss the wild ride in Fightin' Dirty.