The investigation into an assistant U.S. attorney's death leads the team to a related airline whistleblower scandal and the chilling discovery that they don't have much time to thwart terrorists from crashing numerous in-flight commercial airplanes. Dealing with the memory of his brother, who was a 9/11 victim, the case pushes Scola hard to prevent another catastrophe.

When a gunman opens fire at a homeless shelter in Astoria, the team is led toward a killer with connections to a Mexican cartel.