Nuketown Zombies is set after the events of Moon, and at the ending of the multiplayer level from the original Black Ops. A group of radiation scientists are investigating the Nuketown and they discover a soldiers that have been revived by Element 115 from a Nevada base. The zombie soldiers attack the scientists and turns them, and after receiving a distress signal, the Nevada base sends in CDC and CIA agents out to investigate. At arrival in Nuketown, the agents lost communication with Hangar 18 and become stranded…

This was the stage setting for the Nuketown Zombies.

Call of Duty: Black Ops II Unleashes Nuke town Zombies

In response to the overwhelming amount of enthusiasm demonstrated by the Call of Duty community over Treyarch's Zombies mode, we're happy to announce that – in addition to including it in the Call of Duty: Black Ops II Collector's Editions – the Nuketown Zombies map will be made available as a piece of bonus content for the Call of Duty: Black Ops II DLC Season Pass in December.
Fans who purchase the Call of Duty: Black Ops II DLC Season Pass not only get all four epic DLC Map Packs for the discounted suggested retail price of $49.99, but they also get access to the Nuketown Zombies bonus map – available for Xbox 360 first in December with other platforms to follow, plus an exclusive in-game calling card.
For those picking up the CE version of Call of Duty: Black Ops II, the Nuketown Zombies map will be available exclusively starting tomorrow, before it becomes available for Season Pass holders in December.