Quinn Martin uber-producer for television in the 60's & 70's with such classics as the Untouchables, the Fugitive, & numerous other shows tried a science-fiction series.This was a change of pace as most of his shows dealt with crimefighting premises.The Invaders was about architect David Vincent who becomes lost one evening while on an isolated country road.Becoming weary,he pulls off the road into a clearing in order to rest but witnesses a alien flying saucer.As the series went on,he discovers that the aliens are attempting to surreptitiously infiltrate earth's various organizations in government,military,& business in order to conquer us because their homeworld is dying.Since they can look like humans,Vincent never knows who he can trust.This added a creepy paranoia to the show.DV must give up his comfortable life as he launches his one man crusade to convince mankind that aliens are already among us.This was a well written show coming from QM productions.Roy Thinnes is a talented actor but he came off as cold & aloof in the lead part.He never generated the likability & sympathy that David Jansen did in the Fugitive.The spaceships were a cool looking design & the guest stars were excellent.This show belongs in the sf hall of fame.