Spirits of the Air, Gremlins of the Clouds

Siblings Felix and Betty Crabtree live alone in a homestead on a treeless desert plain. Their solitary lives are interrupted by a fugitive with a mysterious past, who gives the name "Smith". Smith is fleeing to the north, a trio of sinister figures in pursuit. The wheelchair-bound Felix tells Smith that the route to the north is blocked by an impassable wall of cliffs, and convinces him that the only way he can travel beyond them is to fly. Smith, at first skeptical, is eventually convinced that his only means of escape lies with Felix's plan to build a "flying machine". Meanwhile, the religiously-addled Betty is convinced that Smith is a demon from hell, and makes her own plans to get rid of him.