Halo 4: Forward Unto Dawn is a live-action miniseries that starts on October 5 and will continue ever week until Halo 4 is released in November. Each webisode will be 15 minutes long and the series itself takes place as a prologue to the upcoming game Halo 4. You can find more information on the Machinima Prime YouTube channel, the channel on which you can find the show itself when it comes out as well as all the trailers released thus far.
Below is the newest trailer in which you meet the squad of Halo 4: Forward Unto Dawn. Check it out! As a side note, for your convenience I will be posting each webisode right here as they are released so you wont miss a thing while you wait for Halo 4 to be released on November 6!