Vermont Bureau of Investigation head Joe Gunther and his team are called in to investigate a series of violent deaths that appear unrelated until telltale clues reveal that they are murders linked by a single drop of unexplained blood left at each crime scene. In their search for the elusive truth, the VBI must plumb the depths of every suspect’s past, every victim's most intimate details, and examine each piece of evidence down to the smallest detail ­– an examination that includes a trip to the Brookhaven National Lab on Long Island and an exploration of cutting-edge forensic technology.