Our protagonist goes to investigate. She enters an upstairs room and a mysterious beeping drones. Further inspection reveals its origin at a frisbee shaped metal object, an unidentified flying object. She watches in terror as a hatch opens from the side. Its passenger, a miniature figure dresses in an odd space suit attacks.
She evades the assault, hiding behind a beam. Her courage mostly restored, she continues the search. Finding the small man in a closet, the woman screams and slams the door. The phone rings, but her intents to retreat the upstairs room are thwarted by another attack?
Agony, terror, confusion. That infernal beeping. Where did they come from? Why are they hurting her? Why her? She's got to get them out. Save herself.
She takes a hatchet to that metal abomination. Chops it again, and again, and again. It must be destroyed.
A transmission: "This planet is inhabited by giants! Do not retaliate!"
She gives a final, critical blow. The ship and its crew are dead. The camera pans out to reveal 'US Air Force' stencilled on the spacecraft. The intruders were human.
(There may be a few errors in this synopsis. I know for sure that I hadn't realized there were two 'invaders'. I must have missed that when I was writing this post.)
If it were not for the twist ending, The Invaders would have been a simple story about an old(?) woman fighting off tiny aliens. Technically, that's still the case, but the fact that the aliens were members of the United States Air Force adds a unique, curious element.
Who were those two men? Why had they visited this planet? Was their visit a mission of peace or war? What year is it? Why did they arrive in a flying saucer and not a shuttle?
Thus this episode of Twilight Zone presents us with a great example of an ambiguous ending.