The action of the dramatic series "Six Four" unfolds in Glasgow, where police detective Christopher O'Neill lives with his wife Michelle, a former police officer. The couple's daughter recently disappeared without a trace, and no one seems to be able to do anything about it. Chris's professional experience and extensive connections are of no help. However, he manages to establish a connection with another, earlier disappearance of a teenage girl in Glasgow. Digging deeper, the hero uncovers a series of police mistakes and rampant corruption.