Driving home late one night from a business trip, an exhausted David Vincent takes a nap at a deserted country spot and is awakened by a landing spacecraft.
Nobody believes him, not his business partner Alan Landers (James Daly) nor Police Lieutenant Ben Holman (J.
D.
Cannon), especially when two aliens disguised as honeymooners claim they were there all night and saw nothing.
Vincent notices, however, that the groom's small finger is extended.
When Vincent returns the next day to question them further, the groom mentions to the bride that he is almost out of time.
A fight breaks out between the groom and Vincent as Vincent insists on seeing the man's hands.
During the fight the man starts to glow.
Vincent is knocked out and awakens in a hospital.
Later, when he is resting at home, someone starts a fire in his apartment from which he barely escapes.
He travels to the ostensible couple's isolated, dying hometown and discovers a secret alien base there.
Unfortunately, he suspects local Sheriff Lou Carver of being an alien instead of Kathy Adams (Diane Baker).
She is actually an imposter who falsely claims to be one of the town's few remaining residents.
When Vincent realizes she is an alien, he looks at her hand and she says, "not all of us are like that." Vincent goes to look for Landers, whom he has convinced to come see what he has found.
His friend is lured into a fatal ambush instead by innocent-looking "Aunt Sara" (Ellen Corby).
The American season-one DVD release also has an extended version of the pilot episode, which was never seen on broadcast television.