The Unknown Man is based on an incredible real life Australian sting operation. Two men meet on a plane and strike up a conversation that turns into friendship. For Henry Teague (Harris), worn down by a lifetime of physical labour and crime, this is a dream come true. His new friend Mark (Edgerton) becomes his saviour and ally. What Henry doesn’t know is that Mark is a seasoned undercover officer - working to convict Henry for the unsolved murder committed years prior.