Mason Gilroy is a former MI6 spy who freelanced all over the world and worked for Tom Strickler. Before Strickler was killed both were working on "secret business". Gilroy has no problem killing innocent people and rather enjoys it, going as far as to kill his own teammates if they fail during a mission (Gilroy informs Michael that a thief partner ("Claude") died due to "complications from his injury", where he only broke his ankle). He is rather good at what he does, committing violent acts and killing people without getting caught or being blamed for it. Michael figures out who he is when Gilroy reenacts his crimes to Michael. He is approached by Michael to join him on his "secret job" but turns Michael away, saying he is not good enough for his job, but after seeing Michael pull off a job he is impressed and decides to hire Michael.