In the penultimate episode of Season 2, we discover that the person organizing the hijack is none other than Robert Lang (Arsher Ali), an MI5 agent who’s working with Stuart Atterton (Neil Maskell), who was arrested in his failed effort to hijack the plane in the first season. He was thwarted by Sam two years ago, and Atterton has been desperate for revenge ever since, and has spent his time behind bars planning Sam’s downfall.