Boarding an international flight to begin a fresh start, Reese (Jim Caviezel) becomes aggravated when it becomes obvious The Machine has a mission for him aboard the plane whether he wants one or not. Despite his initial refusal to help, Reese gets sucked into protecting the programmer (Samm Levine) of an online international narcotics black market whose two U.S. Marshal protectors are both taken out of the equation just after takeoff.
While Reese deals with various problems on the plane including Columbian hitmen, an annoying lawyer, and Israeli criminals, all while making quite an impression on a spunky stewardess (Sally Pressman), Finch (Michael Emerson) asks Shaw (Sarah Shahi) to pay a visit to her old friends as he suspects that The Machine, for whatever reason, has delivered them a number from the relevant list (meaning they aren’t the only ones who received the latest number).
Offering a storyline to return Reese to the fold, “4C” lets the former spy work out some of his anger issues while saving a man who (like many of the numbers) may not deserve to be saved. The episode also allows Shaw time for some payback in confronting the facilitator (Bill English) who set-up Shaw and her former partner to die and have an interesting conversation with Hersh (Boris McGiver) which explains, in part, how the government continues to secretly fund all the various pieces and players tied to The Machine and the numbers it delivers (and why it will go to such links to see the programmer dead before any investigation discloses their existence).