Last week, "Castle" delved into the mysterious three-month long disappearance of the detective. But as Carter Matt noted, the crime drama is not one to dwell on a single story regardless of its importance but immediately goes to the next. The next mystery to solve soars at 39,000 feet. 

Richard Castle and his daughter Alexis will be spending some quality time together and not the way one would expect. The father and daughter's trip to London takes a dark turn when the Air Marshal on the plane is found murdered. Now, it is up to Castle to find the perpetrator before his body count doubles. 

With the help of Alexis, Castle works against the clock to capture the person responsible for the horrendous crime. The pressure builds up knowing that the culprit is inching closer to executing his "fateful plan." 

Kate helps solve the time-sensitive case but does her part on land while her partners take care of the trade in the air. Thus, viewers can expect that this episode will be short of Kate and Castle moments but will surely be loaded with action. 

There to help are Martha Rodgers, NYPD captain Victoria Gates, medical examiner Lanie Parish, and NYPD detectives Javier Esposito and Kevin Ryan. Teamwork is vital to save the passengers in the plane, but in the process, it looks like Castle may find himself at the end of the culprit's gun. 

It will be exciting to see how Castle and the rest of the aircraft's passengers will make it out alive or how they will put a stop to one person's madness. Seeing Alexis springing to action is something to look forward to in this episode. 

"Castle" season 7 episode 21 titled "In Plane Sight" will air on April 27.