Alien: Romulus has a connective thread running through it thanks to Ridley Scott's return to the franchise, and the storytelling may have you trying to piece things together.
Alien hit theaters in 1979 and is led by Sigourney Weaver in her star-making turn as Ellen Ripley. The movie follows the crew of the Nostromo, a commercial starship, as they investigate a distress call in space. They discover an aggressive alien species running rampant on a dead spaceship, which turns their rescue mission into a fight for survival.
While Fede Álvarez's Alien: Romulus is a standalone story between the events of Alien and Aliens, you may wonder how you should watch the Alien movies. The overall story timeline jumps all over the map with stories set in the past and future. You can watch the Alien franchise in chronological order, which would put the prequels first, or in release date order. I suggest starting with the 1979 original and going in theatrical release order. And if you want to make further sense of Alien: Romulus, you can trim the franchise's proverbial fat and minimize your movie marathon to three of the six entries: Alien, Aliens and Prometheus.
A breakdown of how everything ties together is below, but if you haven't seen Alien: Romulus, be warned that spoilers lie ahead.
Read more: 'Alien: Romulus' Trailer Brings the Chest-Bursting Horror Back to Space
How Romulus connects with Alien and Aliens
Since Alien: Romulus takes place between the events of the first two movies, it goes without saying that watching Alien and Aliens will help add further context to the story of Romulus. And after three decades, Ridley Scott returned to the director's chair for 2012's polarizing prequel Prometheus.
These three titles influence the story and aesthetic of Alien: Romulus. To discuss the connections further, I'll be delving into spoiler territory. Scroll past this section if you don't want to know any story details about these movies and how they connect to Alien: Romulus.
Alien: Romulus opens with an intriguing sequence showing Weyland-Yutani scientists retrieving a sample from space. For those familiar with the events of Alien, you'll recognize this as the remains of the xenomorph Ripley battled on the Nostromo, which she shot out of the airlock. The company moved forward with experiments on the sample onboard the Romulus-Remus space station -- and unbeknownst to them, the creature was not dead.
There are plenty of alien battle sequences in Alien: Romulus, which nods to Aliens. The weaponry is similar to what the Colonial Marines used in James Cameron's sequel. Rain (Cailee Spaeny) totes a formidable pulse rifle and eviscerates a bunch of xenomorphs and face-huggers. The action-heavy tone of the movie's second half recall Aliens in delightful ways.
What about Prometheus?
The Prometheus connection begins earlier in the film. After a horde of face-huggers attacks Rain and her friends, they bring a damaged droid named Rook back to life. Ian Holm, who played the evil android Ash in Alien (and passed away in 2020), returns in CGI form here. In Alien, Ash is directed to retrieve the unknown alien species and bring it back to Earth for further testing.
Rook's messaging in Romulus is similar; he refers to the xenomorph as the perfect life form and introduces the crew to the "Prometheus strain." Audiences first got a glimpse of an Engineer -- also referred to as the Pilot or Space Jockey -- in Alien, when the crew landed on the planet and discovered the humanoid's giant skeletal remains. Prometheus clarifies what these creatures were, how they became extinct and the black goo they left behind.
According to Rook, Weyland-Yutani reverse-engineered the substance and bottled it up for further testing. He claimed the serum to be a cure for all human diseases. Spoiler: It's not. Alien: Romulus takes a wild swing in its third act and shows how the Prometheus strain interacts with human DNA. A pregnant and injured Kay (Isabela Merced) injects herself with the black goo. It's not the smartest decision, to be sure.
She goes from not showing a baby bump to delivering the thing in no time flat. The creature she gives birth to quickly grows from newborn-sized to a giant monstrosity and resembles a mashup of human, xenomorph and Engineer.
I said there were three movies this film connected to, but I'd be remiss if I didn't mention Alien: Resurrection. In the fourth movie -- which was written by Joss Whedon -- Weyland-Yutani scientists are yet again conducting experiments. Here, a xenomorph-human hybrid is created by blending the DNA samples from a creature and Ellen Ripley herself. It's not a great ending, to be honest, and I'm not suggesting you watch this one. Heck, even Whedon hated the end result. But the similarities are worth noting.