Like the “Star Wars” saga, the “Alien” franchise is something of a chronological Rubik’s Cube, in that the movies coming out now predate the movies from the 1970s and 1980s on the fictional timeline.

This makes for some onscreen techno-anachronisms.

Example. Ridley Scott’s “Alien: Covenant” takes place prior to the events of the original “Alien” (1979), but since it was filmed in the mid-2010s, it’s an impressive technical achievement, with amazing CGI special effects plunging us deep into outer space and deep into the future.

If you go back and watch “Alien” (as I did), it’s a great movie — but of course it has those late 1970s special effects and production values (and hairstyles), and a nearly 40-year-old vision of what computers and space travel and synthetic robot beings would be like in the year 2122.

“Alien: Covenant” is set 10 years after “Prometheus,” which took place in 2093, so now we’re in 2103, about two decades prior to the events of “Alien,” and if that doesn’t mess with your mind, wait until you see the Dueling Fassbenders portion of the current movie.

This is the third-best “Alien” movie, with James Cameron’s “Aliens” as the standard-bearer, and the original (directed by a young Ridley Scott) close behind. There are high-falutin’ references to the likes of Byron and Wagner and Shelley — but at its core, “Covenant” is a glorified monster movie, with some great “gotcha!” scare moments and, yes, a number of scenes in which a number of supposedly super-smart characters do some really stupid things that get them killed dead-dead-dead.

“I gotta take a leak,” announces one character during a dicey moment when it’s probably best not to wander off.

“Don’t go too far,” says his partner, watching him as he scampers off into the outer-space equivalent of the woods surrounding the cabin in a slasher movie. It’s hardly a spoiler to say in the history of scary movies, when someone says they have to go to the bathroom, they rarely just do their business and happily return to the flock.

After a haunting prelude that looks like it was filmed as an homage to Stanley Kubrick, featuring the “synthetic” artificial human that calls himself David (Michael Fassbender) and Peter Weyland (Guy Pearce), the billionaire founder of the Weyland Corp., we join the Covenant, a massive colony ship on a seven-year journey to a faraway planet.

There’s only conscious entity aboard Covenant: Walter, a next-generation synthetic who looks exactly like David, which is convenient seeing as how Michael Fassbender plays both synthetics. Everyone else is in the midst of a multi-year cryogenic hyper sleep — but Walter has to awaken the crew when a freak accident plunges the ship into emergency mode.

The beloved captain of the ship dies, leaving the by-the-book, self-doubting Oram (Billy Crudup) in command.

(Sidebar: It’s a bit of a distraction that the quickly-killed-off captain of the Covenant is played by a well-known star. We keep wondering if this character is going to somehow return, because why else would a popular leading man take such a tiny role?)

Key crew members aboard the Covenant include the smart and resourceful Daniels (Katherine Waterston), who was married to the late captain; the calm and collected Karine (Carmen Ejogo), who is married to the CURRENT captain (Crudup), and the wisecracking, cowboy-hat-wearin’ pilot Tennessee (Danny McBride), who is married to the tough-as-nails Faris (Amy Seimetz).

(All of this coupling makes sense, when you consider the goal of the mission is to land on a distant planet and stay there for the duration.)

When the Covenant receives a mysterious distress signal, Oram believes it could lead them to a paradise planet even more suited to human life than their original planned destination. Ignoring Daniels’ warnings, Oram directs the ship to the mysterious but lush, warm and inviting planet.

Of course, there’s trouble lurking just around the bend. It’s only a matter of time before nasty creatures rear their ugly heads and bare their sharp teeth, and various crew members are dispatched in gruesomely entertaining fashion.

Also occupying the planet: none other than David, the synthetic from “Prometheus,” who tells the crew he’s been here for the last 10 years.

Enter the Dueling Fassbenders.

David becomes a sort of mentor to Walter, even though Walter is the more advanced and sophisticated synthetic. Fassbender’s work in these two roles is an understated wonder to behold; he creates two distinct characters that often interact with one another, and he manages to infuse each synthetic creation with unique personality traits.

That said, at least one bit of interaction between Walter and David is just goofy and unintentionally funny. And a big plot revelation deep into the story is one of the least surprising “twists” in recent film history.

“Alien: Covenant” includes a number of nods to the first two “Alien” movies, to the point where it sometimes plays like a Greatest Hits collection.

At least they’re covering a classic.

★★★

20th Century Fox presents a film directed by Ridley Scott and written by John Logan and Dante Harper. Rated R (for sci-fi violence, bloody images, language and some sexuality/nudity). Running time: 123 minutes. Opens Friday at local theaters.