movie begins aboard the experimental SSV Normandy, commanded by
Captain Anderson and his executive officer, Commander Shepard.
The Normandy is being sent to the human colony world of Eden
Prime to recover an unearthed Prothean beacon. To assist in
recovering the beacon, the Citadel Council, the main government
for most of the galaxy, have sent one of their top agents, a
turian "Spectre", named Nihlus.
Nihlus, Shepard, and a small team discover that the Eden Prime
colony is under attack by alien synthetic life-forms known as
the geth, led by a rogue turian Spectre named Saren Arterius,
who kills Nihlus. After the battle ends, Shepard locates the
beacon and receives a vision of biological creatures being
slaughtered by machines.