Even if Prometheus tended to detach from the Alien franchise, some elements in the movie interconnected so well that a sequel was imperiously necessary. And so, Ridley Scott came up with Alien: Covenant to answer some of the questions in Alien and Prometheus. But he realize that a sequel won’t do it, and there are two more to follow Covenant. All four will serve as prequels to 1979's Alien.
The official synopsis introduced us to what will happen in the movie.
“Ridley Scott returns to the universe he created in ALIEN with ALIEN: COVENANT, the second chapter in a prequel trilogy that began with PROMETHEUS "” and connects directly to Scott's 1979 seminal work of science fiction. Bound for a remote planet on the far side of the galaxy, the crew of the colony ship Covenant discovers what they think is an uncharted paradise, but is actually a dark, dangerous world "” whose sole inhabitant is the "synthetic" David (Michael Fassbender), survivor of the doomed Prometheus expedition.”
In a recent interview for The Wrap, where he mostly talked about The Martian, Scott revealed more about the story in Alien: Covenant, and what questions the movie will answer.
Alien: Covenant will bring back monsters from 1979 sci-fi horror classic
So it seems that we will meet again with series’ iconic Xenomorphs, we will find out about Engineers’ origins and their motivations.
“They're going to go to the planet where the engineers came from, and come across the evolving creature that they had made. Why did they make it? Why would they make such a terrifying beast? It felt bio-mechanoid, it felt like a weapon. And so the movie will explain that, and reintroduce the alien back into it.
There was always this discussion: Is Alien, the character, the beast, played out or not? We'll have them all: egg, face-hugger, chest-burster, then the big boy. I think maybe we can go another round or two.”
If we connect the official synopsis to what Scott recently revealed, it seems that Elizabeth Shaw is dead or missing, and the crew of the Covenant will meet with the sole surviving inhabitant of the planet, David and the evolved version of Xenomorph creature from the last film.
