(Originally published July 7, 2008)

When I was a kid, I loved the outer-space adventures of the original “Star Trek” series, which I found entertaining and thought-provoking. But another series at that time managed to scare the living bejeezus out of me — and still does.

 That program is “The Invaders,” introduced each week with an ominous opening sequence:

The Invaders: Alien beings from a dying planet. Their destination: The Earth. Their purpose: To make it their world. David Vincent has seen them. For him it began one lost night on a lonely country road looking for a shortcut that he never found. It began with a closed, deserted diner and a man too long without sleep to continue his journey. It began with the landing of a craft from another galaxy. Now David Vincent knows that the Invaders are here, that they have taken human form. Somehow, he must convince a disbelieving world that the nightmare has already begun.

The show’s first season is now available on DVD and I’ve been watching “The Invaders” with new appreciation. Unlike a lot of series from that era, it sure holds up. The few effects are done well and the attention paid to lighting, music and art direction rivals that of many contemporary theatrical films.

Cloned from Quinn Martin Productions’ “The Fugitive,” this show follows “architect David Vincent,” played by 29-year-old Roy Thinnes. Although he gains allies in the second season, Vincent initially leads a desperate, one-man campaign to expose the vanguard of an alien invasion. The aliens themselves are among the reasons why the series proved so frightening. They’re only shown in their human forms, which often aren’t 100 percent perfect, and can be identified usually -— but not always -— by a misshapen pinkie finger.

To maintain their human shape, the invaders must periodically step into regeneration tubes. Only occasionally, a human gets to see an invader in its actual native form. Those who do often are driven to the point of madness.

And although within the context of the series these humans see the invaders, viewers never do. We see only the humans’ terrified reaction to these aliens, which makes their presumed appearance all the more terrifying.

Almost as terrifying are the ways in which the invaders infiltrate human society. They’re small-town sheriffs, government officials, leading scientists -— and in one notable episode even a stripper played by Suzanne Pleshette. It’s a rich vein of paranoia later mined to similarly chilling effect by “The X-Files.”

Although it’s difficult to believe these invaders really are here from “another galaxy,” they’ve definitely come a long way and their resources are being stretched to near the breaking point. Their most effective weapons are seldom a large scale effort, but rather treachery, brainwashing — and a nasty little disk that when pressed to a human’s neck induces death by cerebral hemorrhage.

But the biggest problem facing David Vincent is that it’s next to impossible for him to prove that the invaders are here because when one is injured or shot, they just about always go up in a blaze of spontaneous combustion.

Most of the episodes in this set have been transferred in crisp color and with a rich soundtrack that allows Dominic Frontiere’s eerie musical score to properly frost your spine. Roy Thinnes, now 70, introduces each episode and is also featured in a supplemental interview in which we learn that some of the show’s crew thought UFOs were no laughing matter.

Series creator Larry Cohen narrates much of “The Innocent,” which, although he didn’t write it, is his favorite episode. Cohen offers up some interesting stories, but his narrative tends to wander. And he also gripes way too much about how his “Created by Larry Cohen” credit is at the end of each episode rather than at the beginning. Larry: If it’s any consolation, I noticed and remembered it. So much so that when I saw “It’s Alive,” “Q” and “The Stuff” years later, I thought wow, this is by the guy who created “The Invaders”!

Genre fans will especially enjoy “The Innocent,” which was originally telecast March 14, 1967. It’s not hard to see why Cohen counts this episode among the best. In it, Vincent is abducted and taken aboard a flying saucer by one of the invaders’ leaders — played by Michael Rennie, famed for his portrayal of Klaatu in the seminal saucer movie “The Day the Earth Stood Still.”

This episode illustrates how “The Invaders” sparingly used special effects to such advantage. Vincent is driven to a mission revival ranch house and taken to see Rennie — and then he’s escorted into the back yard where he’s manhandled into the saucer. It all plays out as matter of factly as if hoods were stuffing a snitch into a Lincoln.

The saucer design itself no doubt tapped into its own wave of paranoia. Inspired by the spacecraft reported by 1950s contactee George Adamski, it was in a way the series co-star, a character that all of us hoped to see more of than we did.

Perhaps the saucer’s best appearance is in “The Mutant,” which finds David Vincent tracking down reports of a crashed saucer in the Desert Southwest. The scene in which he stumbles upon aliens repairing their saucer does a great job of laying the early groundwork for vectoring the Roswell legend.