Season
Episodes
Beachhead
An architect's close encounter with a spaceship leads him to investigate a small town's hydroelectric plant.
The Experiment
David Vincent meets with an eminent astrophysicist who has proof that aliens are invading the planet.
The Mutation
With the assistance of Vicki, a nightclub stripper, Vincent continues his search for an alien spacecraft.
The Leeches
Vincent is called on by a renowned electronics expert who fears he may soon be abducted by alien invaders.
Genesis
Vincent's search for aliens lead him to an underwater sea lab.
Vikor
A dying telephone lineman's fantastic story leads Vincent to investigate a huge industrial complex owned by a famous war hero.
Nightmare
Vincent travels to a small town to check a possible link between the aliens and an attack of carnivorous insects.
Doomsday Minus One
Vincent is called upon to help avert possible alien infiltration at a government nuclear test site.
Quantity: Unknown
While investigating the theft of a mysterious cylinder from the site of a plane crash, Vincent is captured and suspected of being an alien.
The Innocent
The aliens take David Vincent up into their spaceship and then attempt to prove they have nothing but peaceful intentions by showing him what they've done to a desert valley. But all is not what it seems.
The Ivy Curtain
Vincent discovers that a school is being used by the aliens as an indoctrination center.
The Betrayed
Vincent discovers a mysterious computer tape that could offer proof of the alien invasion.
Storm
Vincent is contacted by a meterologist to help investigate the suspicious nature of a hurricane along the Eastern U.S. coast.
Panic
The invaders and Vincent race to capture a wounded alien whose touch brings on freezing death.
Moonshot
Vincent helps a security official investigate the deaths of two lunar astronauts in a strange red fog.
Wall of Crystal
David's brother, who also thinks he is crazy, is kidnapped by the aliens who intend to destroy the oxygen in our planet's air.
The Condemned
The invaders frame Vincent for the death of an owner of an electronics plant who had made discoveries about the aliens.
Cast
Roy Thinnes
David Vincent
Diana Hyland
Sherri Vikor
William Windom
Major Rick Graves
Kent Smith
Stan Arthur