Vincent is accused of murder after an explosion kills a senator seconds after he delivered a warning about an alien's presence.
A lovely alien (Suzanne Pleshette) seeks Vincent's help in controlling synthetic emotions implanted in her by alien scientists.
Two alien fugitives (Barry Morse, Diana Muldaur) contact Vincent to ask for his help in stopping the invasion of Earth.
Witnessing an alien incineration at a religious shrine, a young woman (Barbara Hershey) believes she had a miraculous vision.
Vincent has only 24 hours to prove a man recommended for appointment to an important post in the space program is an alien.
A high-ranking general (James Daly) asks Vincent to arrange a meeting with alien leaders to discuss peaceful coexistence.
Vincent learns crime syndicate members are searching for extraterrestrials to recover a shipment of stolen narcotics.
A vicious dog convinces Vincent aliens are responsible for a friend's (Charles Aidman) recent institutionalization for insanity.
Vincent is accused of murder after aliens sabotage his plans to jam alien radio signals used to guide saucers to Earth.
Vincent's college buddy expresses concern about peculiar experiments conducted by his brother at their sanitarium.
Aliens infiltrate a publishing empire as the first step in taking over the nation's news media; guest Kent Smith, Nancy Kovack.
Aliens threaten Earth with severe recrimination if Vincent does not release a high-ranking alien hostage (Alfred Ryder).
A pretty psychologist (Carol Lynley) offers Vincent a chance to escape when extraterrestrials capture him for interrogation.
A communist delegate calls for Vincent's help when an alien intruder is caught inside the building; guests Dana Wynter, Fritz Weaver.
Vincent secures alien X-rays and wins support from a government UFO specialist, until he suggests the man's daughter is an alien.
Vincent seeks to expose evangelist Brother Avery (Pat Hingle), who wins followers with his ability to glow.
An attractive alien informer (Diana Hyland) offers Vincent help in stopping an international assassination plot.
Vincent learns of an alien plot to assassinate the world's leaders at a conference; guest William Windom.
Vincent smuggles himself aboard an alien saucer, hoping to find a treatment center for diseased aliens; guest William Sargent.
Vincent pursues an alien (Gene Hackman) whose case contains spores that will produce mature aliens when opened.
Vincent's friend Charlie Gilman (Don Gordon) discloses an ulterior motive for killing an alien during his trial for murder.
A nurse (Barbara Barrie) tends to a mortally injured alien (Richard Anderson) who begins a horrifying transformation.
Vincent warns a town about an alien (Joe Maross) incarcerated for murdering a doctor who tried to examine him.
Vincent seeks work at a resort where a frightened hotel manager made an odd revelation shortly before committing suicide.
To capture an alien ship, Vincent seeks a man (Dabney Coleman) considered a crank for reporting saucer landings.
A doctor dies mysteriously after reporting the death of a woman who appeared to be alive but lacked a heartbeat.
Aliens frame Vincent for the death of a communications plant owner (Ralph Bellamy) who stole an important alien file.
Extraterrestrials discourage Vincent from publicizing proof of their presence by capturing his brother (Linden Chiles).
Vincent's investigation of the deaths of two astronauts in an eerie red fog leads him to suspect human culprits.
Vincent races to find a sick alien (Robert Walker), whose touch freezes people, before other aliens reach him.
A meteorologist (Simon Scott) summons Vincent after seeing a freak hurricane swerve to spare a fishing village.
Vincent takes a mysterious tape he found in an abandoned train car to a cryptographer (Norman Fell); guest Ed Begley.
Vincent learns that Midlands Academy is being used as an indoctrination center for newly arrived aliens; guest Jack Warden.
Aliens kidnap Vincent and take him aboard their saucer, where a spokesman (Michael Rennie) tells him he will visit Utopia.
Vincent investigates after security guards are ambushed while transporting a mysterious cylinder found in a plane wreck.
The security chief (William Windom) of a major nuclear testing facility seeks Vincent's help to avoid alien interference.
A teacher (Kathleen Widdoes) with a history of mental instability tells Vincent she witnessed carnivorous locusts.
Vincent suspects extraterrestrials have overrun a manufacturing complex after a dying man reports seeing a glowing man inside a tube.
Vincent is led to a sea lab where life is created, while a traffic cop goes insane after looking inside the staff's station wagon.
An electronics expert (Arthur Hill) asks Vincent to help him avoid the fate of six others abducted by aliens.
Claiming to know where the saucer landed, a local stripper (Suzanne Pleshette) leads Vincent into the Mexican desert.
Vincent prevents the assassination of an astrophysicist, who plans to reveal proof of the aliens' presence.
David Vincent (Roy Thinnes) sees a flying saucer land, but when he returns with police, they find only a honeymooning couple.