When five sorority girls inadvertently cause the murder of one of their sisters in a prank gone wrong, they agree to keep the matter to themselves and never speak of it again, so they can get on with their lives. This proves easier said than done, when after graduation a mysterious killer goes after the five of them and anyone who knows their secret.

UNSC Cadet Thomas Lasky must conquer his inner fears and join forces with super-soldier John-117 to take down a massive faction of the Covenant.