Castle and Alexis are on a flight to London so that he can speak at The Sherlock Holmes Society when Castle notices something is wrong with the flight crew. Flight Attendant, Farrah knows who he is and that he consults with the NYPD and confides that their Air Marshal, Kyle Ford has gone missing. After checking the entire plane, they find the man’s body in the baggage area.
Via cell phone, Alexis helps Lanie figure out how the man was possibly murdered and Rick works as a representative of the NYPD and helps the crew figure out if they have a terrorist on their plane.
The list of suspects grows as they realize they have a passenger with a fake passport and possible ties to ISIS, the Air Marshal's disgruntled girlfriend who was recently fired by the airline and a private courier service tasked with delivering a multi million dollar watch safely to London. Beckett encourages Castle that he is more than capable of conducting interrogations after watching her do it hundreds of times over the years. But will they find the killer before they strike again?
Watch Castle Season 7 Episode 21 Online right here at TV Fanatic.