Sierra Four is most identifiable by the scar across his chin. During his fight with Six on the fireworks barge, Sierra Four reveals that he is also a Sierra agent. He further reveals that he was recruited by Donald Fitzroy and trained in a Tel Aviv black site, just like Six had been. Amidst his last breaths, he hands Six the stolen hard drive, telling him that Denny Carmichael can’t be trusted and must be taken down before he takes down Six.