Deep Underground is the second level of Area 51. It is a cutscene, narrated by Ethan Cole and showing HAZMAT Team Bravo's descent into the base.
Plot[]
The elevator carrying Bravo Team descends as Ethan Cole narrates. U.S. military personnel are running around. Experimental projects are seen, as well as quarantined civilians. Infected soldiers attack a scientist and soldier. The military is then seen trying to contain the virus; soldiers throw a body into a burning pile and a forklift knocks a helicopter off of a ledge, destroying it.