Demon Within

"All NATO units have been scrambled. This needs to be our finest hour, gentlemen."

- Derek Bosworth Demon Within is the sixteenth mission in Black Ops 3: The Finale. Daniel Mason and the Navy Seal squadron hunt down Daniel's former cyber ops teammates before they release the Nova 6 gas. It is the longest level in the campaign.

Characters

 * Daniel Mason (playable)
 * Jacob Hendricks
 * Guan Ye
 * Dylan Stone
 * John Taylor (KIA)
 * CORVUS (KIA)
 * Sebastien Diaz (KIA)
 * Sarah Hall (KIA)
 * Gareth Henderson (Heard-Only)
 * Derek Bosworth (Heard-Only)
 * Han Sheng (Heard-Only)

Level Briefing
Encryption #4TF4-8A Designation:

Daniel Mason  in charge of hunting down John Taylor's rogue team, though Taylor is now considered friendly

Taylor's team has been tracked to Chongqing

All Navy Seals have been mobilized to neutralize all Cyber operatives

12 hours until nuclear destruction at deadline of August 7, 2065

Plot
Daniel Mason, Jacob Hendricks, Guan Ye, and Dylan Stone arrive in the crumbling city of Chongqing soldier, with the support of a Navy Seal squadron, to take down Daniel's rogue former teammates, Sebastien Diaz and Sarah Hall. The group meets up with John Taylor, who is believed to have escaped CORVUS's infection and has returned to normal. Daniel and Hendricks are still suspicious when they link up with Taylor.

The city is under attack from Cordis Die and the Cyber Ops Robotics Armory - which means the main enemies of the level are high-level revolutionaries, Mercs, Grunts, Manticores, and RAPS - all of which are difficult to beat. They eventually arrive in the city's square, where Hall is located inside a Manticore. After a boss fight, Hall is defeated, and Daniel sadly kills his former teammate with a bullet to the head. Taylor, who has been acting twitchy during the mission, accidentally kills a Seal in friendly fire when a group of Grunts attack them.

The group then heads to the banking district to eliminate Sebastien Diaz. Diaz calls in a Swarm on his position, forcing the team to head inside and travel to Diaz's location indoors on skybridges and connected buildings. Upon arriving on top of Diaz's location, Diaz attempts to kill them using an XM-53, collapsing the building they're in while Diaz runs out into the street. Daniel avoids this, jumps into the street and chases Diaz, who is cornered in alley. In desperation, Diaz activates a canister of Nova-6, but Daniel quickly grabs the canister and shoves it into Diaz's throat, punches the canister, then backs away. The gas overwhelms Diaz's cybernetics and kills him.

Henderson then radios in, stating that if CORVUS was truly shut down, then there would be no reason for the Cyber Ops to continue his orders. Taylor begins to scream and collapse, and the team realizes that CORVUS must still be alive in Taylor's mind. Using the hacked DNI of Donnie Walsh, Daniel syncs DNIs with Taylor and enters his mind.

Daniel awakens in a warped simulation of Taylor's greatest study - Daniel's own grandfather, Alex's, escape from Vorkuta gulag. Taylor arrives beside Daniel, and together, the two successfully re-enact some of the uprising, and corner CORVUS. Knowing the only way to defeat the AI is to destroy his own mind, Taylor orders Daniel to purge his DNI. Knowing that Taylor will die, Daniel reluctantly does so while Taylor holds CORVUS at bay. CORVUS is deleted, and Taylor thanks Daniel one last time before being deleted from the simulation as well.

Daniel re-awakens in reality above the dead body of John Taylor, with seemingly no time passing. Radio transmissions reveal that across China, the Cyber Ops units are returning to normal and laying down their arms. Nuclear war and the destruction of society has been averted.