Somehow, an Australian website got its hands on the script for Ridley Scott's return to the Alien franchise and posted all kinds of info—until Fox made them take it down. But we sniffed it out and present it for your consideration.
One thing to be wary of: It's unclear which version of the screenplay What's Playing obtained, the Damon Lindelof rewrite or Jon Spaihts' original draft. But here's the pertinent plot information (which, again, is full of stuff you might not want to know):
The space jockeys—referred to in the script as Growers—are terraformers, who travel the cosmos turning barren rocks like LV-426 into habitable planets.
Somehow, the Growers need the aliens to do so—but only in their unhatched, egg state.
The Growers are keeping two humans—named Fin and Karik—as prisoners. These two men are forced, thanks to mind control, to have sex. The Growers are looking to breed humans, but can't comprehend gender. Awkwardness ensues.
There is a spaceship crew, two of which will be female: Oliver, a rough-and-ready warrior like Aliens' Vasquez, and Truks (rumor has it that Gemma Arterton will play this role, so it's safe to assume that it's a little girlier).
The alien as we know it doesn't appear until the second half of the film. Presumably when things go all kinds of wrong. As they are wont to do in Alien movies.
(via Spoiler TV)