Liam Neeson stars as a US Federal Air Marshal on a busy international flight from New York to London.
As the aircraft reaches cruising altitude, he receives a series of bizarre and threatening text messages demanding that the airline transfers a ransom of $150m into an offshore account. Failure to comply will result in one passenger on the flight being killed every 20 minutes. The threats turn out to be genuine and everyone on board becomes a suspect. While Captain David McMillan (Linus Roache) and his crew including ballsy flight attendant Nancy (Michelle Dockery) attempt to maintain calm in the claustrophobic aircraft, Marks searches for answers. However, his gung-ho one-man crusade is hampered when authorities discover that the bank account is registered under his name and Marks is branded a terrorist.