“In Plane Sight” is a great episode to clear our minds after a somewhat dismal showing in last week’s “Sleeper” where we were supposed to learn about Castle’s mysterious disappearance. This week, Castle (Nathan Fillion) and Alexis (Molly C. Quinn) take a mini father/daughter vacation to London but encounter more than turbulence during their flight. When Air Marshal Kyle Ford (Brian Perry) is found dead in the cargo hold, Oceanic Air flight 57’s captain (Lisa Kaminir) asks Castle to step in to help solve the mystery.