You can only imagine how many times Fede Alvarez has seen “Alien.”

The filmmaker, whose credits include 2016’s well-received tension-filled horror-thriller “Don’t Breathe,” this week unleashes “Alien: Romulus” into theaters.

A bit of a mixed bag overall but certainly at times thrilling and at others scary and unsettling, the movie is designed to be a bridge that forms a trilogy; its story is set about 20 years after the events of director Ridley Scott’s aforementioned 1979 science-fiction-meets-horror classic and not quite four decades before its first sequel, 1986’s “Aliens,” a more action-heavy offering helmed by James Cameron.

“Alien: Romulus” offers myriad elements and moments similar to those in the film that started the now massive franchise. (“Romulus” also boasts one rather strong connection to “Alien,” but detailing that would be to venture into spoiler territory. Let’s just say we’re interested to see how it’s received by fans.)

The fifth installment in the “Alien” saga — or, if you count crossover offerings “Alien vs. Predator” (2004) and “Aliens vs. Predator: Requiem” (2007), the seventh — “Romulus” takes us back to the far future after the two Scott-directed prequels, “Prometheus” (2012) and “Alien: Covenant” (2017), to a time when human colonies have popped up on other planetary bodies.

We meet this film’s young protagonists in one such colony, Jackson Star, where the mining operation of the franchise’s embodiment of corporate greed, the Weyland-Yutani Corporation, has caused sickness and claimed lives, such as those of the parents of 25-year-old Rain (Cailee Spaeny).

While sticking close to her “brother,” Andy (David Jonsson) — an android, or “synthetic,” created by Weyland-Yutani and taken in and fixed up by Rain’s father after it had been discarded — Rain dreams of a better life off-world.

After she is screwed over by the company, which suddenly requires several more years of work from her before she can leave the colony, she is recruited for a scheme ginned up by other young people hoping to depart for a planet that is a several years’ journey away. Ultimately, they need the services of Andy, who, they hope, will be able to interface with tech aboard a decommissioned space station, giving them the access they need to steal cryo pods, devices that would allow them to survive such a trek while sleeping.

Once aboard the station, the Renaissance, problems arise quickly for Rain, Andy and their cohorts: Tyler (Archie Renaux, “Shadow and Bone”), who’s Rain’s ex and with whom she still shares a connection; Kay (Isabela Merced, “Sicario: Day of the Soldado”), Tyler’s sister; Bjorn (Spike Fearn, “Back to Black”), who has reason to distrust synthetics; and Navarro (Aileen Wu, in her feature film debut), a tech-savvy type who is like a sister to Bjorn.

Soon enough, those problems include the familiar “facehugger” alien parasites that incubate a victim with an embryo of the dreaded Xenomorph monsters that are synonymous with the “Alien”-verse. As should come as no surprise, humans aboard the Weyland-Yutani-owned station had been holding scores of the facehuggers captive in tanks.

Soon enough, Rain and Andy must make a harrowing journey to the “Romulus” half of the station if they are to survive long enough to escape it.

Spaeny makes for a reasonably compelling heroine here. In her hands, Rain is relatable and caring but also tough. The best performance, however, is turned in by Jonsson (“Industry”), whose Andy starts as one thing — a bad joke-loving, beaten-down robot — and evolves into something else.

The rest of the characters? Entirely forgettable — more an indictment of Alvarez and his co-writer, frequent collaborator Rodo Sayagues (and director of 2021’s not-so-well-reviewed “Don’t Breathe 2”), than of the actors.

Still, there’s a lot to admire with what Alvarez has accomplished here. Unsurprisingly, his movie, just as “Alien” does, saves a little something for its final few minutes — and, oh baby, is it something.

Just know you won’t be able to UN-see it./Tribune News Service

(“Alien: Romulus” contains bloody violent content and language)

“ALIEN: ROMULUS”

Rated R. At the Landmark Kendal Square Cinema, AMC Boston Common, South Bay Center, Causeway, Alamo Drafthouse Seaport and suburban theaters

Grade: B-