It starts with a gloomy, mysterious melody, reminiscent of the music played when facing the Flood in Halo 2. At around 0:40, the music quickens to a rapid drums beat. Later on, a soft melody is added to the background. At 2:10, choir starts a major melody, with drums and orchestral accompaniment. Near the end, the drums get dramatically louder, and the song fades to a close.
It runs for 3 minutes and 1 second (3:01).