From The Perry Mason TV Show Book
Janet Morris is arrested for poisoning her doctor-husband just before he flew to his death in his private plane. However, further investigation reveals that the dead man in the plane is not Dr. Morris after all, but one David Kirby. Dr. Morris is alive and well and living it up incognito in Mexico with his girlfriend.
Tragg still prosecutes Janet for murder but Perry suspects there is a master plan behind the scenes and looks for another killer.