Non-Stop (2014) on Netflix

Plot summary

Bill Marks, a former New York police officer who became a federal air marshal, drinks whiskey at the airport before boarding Flight 10 to London. In business class he ends up beside Jen Summers, who traded seats to get a window. Out over the Atlantic his secure phone receives messages: a passenger will be killed at twenty minute intervals unless $150 million reaches a named account. The sender knows Marks smoked in a lavatory. Marks breaks protocol and confides in Jack Hammond, the flight's other marshal, who treats the messages as a joke. Captain David McMillan hears the report; a manifest cross-check would take too long, so the TSA is asked to trace the account while Marks studies the cabin camera feeds in the galley with Nancy and Jen, watching for a passenger who is typing.