When planes are crashing from an unknown cause the government at first suspects mechanical trouble. However when a survivor of one of the crashes mentions that a mysterious plane with large X's on the wing was spotted just as the plane exploded its realized that something more is afoot. Its quickly deduced that the murderous pilot is an ex-airmen from the great war, so all of the airmen in the area are rounded up both to help hunt down the killer and to allow for all the suspects to be in one place.
This is a breezy little mystery with planes engaging in dogfights, secret panels, secret rooms, murder on the ground (in addition to in the air), romance and various other mystery standbys. Its a great deal of fun to try and guess who Pilot X is from among all of the possible suspects, though you'll probably have it narrowed down to one or two possibilities from the get go. It moves along at a nice clip and keeps you engaged for its just over an hour running time. Think of it as a aerial version of Ten Little Indians.
Worth a bag of popcorn, a soda and an hour of your time.