Nightmare at 20,000 Feet races. Director Donner and writer Richard Matheson pace out the episode perfectly–though it being a “Twilight Zone” episode means they can also utilize some of the series’s credit formula to great effect.
The episode has a few phases. Introducing William Shatner and Christine White (they’re married, he’s just recovering from his mental breakdown while on an airplane), putting Shatner in the window seat, him seeing the gremlin. Those events all happen in the first phase. Second is him trying to get help with the gremlin, third is him taking it into his own hands. These phases take place inside a three act structure. It’s an intense story, made more intense through the direction and then Shatner’s performance.
Shatner does fantastic work, as the viewer has to believe they’re going crazy with him. There’s a hesitation; Shatner, Matheson and Donner make sure the viewer gets past.