1. A Planet.
2. Going In.
3. Engineers.
4. Life.
5. Weyland.
6. Discovery.
7. Not Human.
8. Too Close.
9. Try Harder.
10. David.
11. Hammerpede.
12. We Were Right.
13. Earth.
14. Infected.
15. Hyper Sleep.
16. Small Beginnings.
17. Hello, Mommy.
18. Friend From The Past.
19. Dazed.
20. Space Jockey.
21. Collision.
22. Debris.
23. Planting the Seed.
24. Invitation.
25. Birth.

Hammerpede

That planet at the opening is actually Earth, millions of years ago, and that Engineer/Space Jockey is a rogue/renegade, who created humans life on Earth by dissolving his own DNA when he drinks that black goo and creating the first basis of human. Basically, human's were created in a lesser version of the engineer's DNA image. Ever heard of this passage "God created man in his own image".
That what it means actually God(Engineers) created man in his own image(Engineer's DNA)

So for some reason all the other Engineers, doesn't approve this creation of humans, so the whole movie is about the other Engineers trying to fix his mistake by destroying humanity.

or it could be the other way around, maybe Engineer's purpose were to create life, but those Engineers in the planet Prometheus landed on are the rogue Engineers and believes human shouldn't exist for some reason, so they deceided to wreck some shit on earth and destroy every living humans

Peter Weyland is an old man, and he's actually inside Prometheus. He wants to steal the Engineers' technology to become immortal, and uses the elephant Space Jockey suit.

Vickers is Weyland's daughter, but she hates him and resents her "brother", David. She wants Prometheus to fail so Weyland can finally die.

The Engineers were all killed by something that they created and that got out of control. It's implied that the Space Jockey, the last Engineer, sabotaged the experimented and exterminated his own race because the other Engineers killed the Space Jockey's brother. Said brother terraformed Earth and created humans, but made them too advanced and shared too much of his knowledge with his "children".

Holloway is infected by a "virus" created by the Space Jockey, and manipulated by him into having sex with Shaw. She becomes pregnant, and her offspring is the Xenomorph Protoform, a creature that is able to seed into other creatures by laying eggs in their mouths.

Movie ends with the first chestbusting.