Spoilers for Halo 4 and tie-in book The Thursday War lie below.
Major plot details and story spoilers appear to have been inadvertently outed by 343 Industries' latest Halo 4 trailer. Oops.
Included in the footage is a blink-and-you'll-miss-it shot of the game's script, which names the title's main antagonist.
Halo 4's primary villain is an ancient Forerunner named Didact. The Covenant believe him to be a living god, and seek to wake him from some kind of stasis.
Didact was previously seen in the Halo anime, as well as Halo novel Cryptum.
Halo Reach's Dr. Halsey reappears to aid Cortana, Master Chief's decaying blue AI helper, who is now able to project multiple versions of herself at once.
Master Chief and Cortana will later fight a pivotal battle with Didact. The script provides detailed information as to its physical nature:
Didact: "Compassion for mankind is misplaced."
Chief: "I'm not doing this for mankind." Chief then charges at Didact.
Cortana rushes towards Didact and jumps all over him (legs, arms, chest, back).
Several takes of "Cortana" tackling and climbing on random objects at full speed.
Didact is attacked by Cortana. He attempts to swat at Cortana as a means of self defence.
Didact unclenches his fist and drops Chief.
Several lines of text from Halo: The Thursday War expand on Didact's role.
"Don't you see it? Requiem. That's where the Didact was hidden. That's where they say he waits."
"He tried to fight the flood. He tried to destroy the humans."
"Didact sleeps and must never be woken."
We've freeze-framed the script page seen in the trailer below. Click it to expand the image and take a closer look.