UNSC Savannah was put into service to research Promethean technology. The goal was to unlock the power of the Sentinel Beam and use it in the UNSC's weapons. The secret was discovered, and the crew on board has been silent since. The last transmission simply said, "We did it, we finally did it. We will begin testing today on the prototype."
The mission is to locate the prototype at all costs. The crew is expendable.
-- Each area has a button. There are 3 overall to open the door to the prototype. Each button has to be pressed to activate the next.