Wikia HT - Adam

Adam, although not originally identified as such, is the Air Marshal aboard Flight 234, and thus the man who arrests Chance after the latter's run-in with Shaun. The marshal is later disarmed by Laura, who believes Chance and his plan give everyone on the plane better odds of survival than Adam doing things by the book. He provides the essential insight (to Winston) that the second assassin's failure to free Shaun is, in itself, highly suggestive. Presumably his official report on the incident paints his own activities in a better light than the episode. Adam may or may not take credit for foiling the conspiracy, as he in not seen during the denouement.