Forward Unto Dawn

Available on YouTube, and on Halo Waypoint, Halo 4: Forward Unto Dawn is a live-action digital series that takes fans back to the terrifying beginning of the Human/Covenant war, when the Master Chief inspired a young cadet who would eventually become a leader aboard the UNSC’s greatest vessel: the UNSC Infinity. Halo 4: Forward Unto Dawn tells a story leading into the events of Halo 4.

I just watched all five episodes and it's definitely worth your time.  They're about 15 minutes each, and surprisingly well produced.  I recommend watching them via Halo Waypoint on your Xbox 360 so that you can experience them in 1080p surround sound.  Short of that, you can watch them online at Waypoint.

After you're done watching that, this will tell you everything you want to know about Kelly-087.