The story starts when a meteor hits Earth next to Shi no Numa, the contents is discovered where they find an alien with the ray gun and a strange substance name Element - 115 which is later used to create the Wunderwaffe DG-2. They take the alien to Area 51 and element - 115 is researched at Shi no Numa. The alien will be part of the alien terrorist mode in MW2. It has been confirmed now.

At Der Riese Dr. Maxis is experimenting with teleporters, in test 5 the subjects teleport but not to the mainframe, instead they go to around a mile off Nacht der Untoten where they are transformed to zombies which had been a problem in all the other experiments. At the same time a US plane crashes nearby with all five unharmed. Four go off to check out a nearby bunker while the pilot stays with the plane. You see the pilot get killed at the beginning in the cut-scene, the others are then bombarded with zombies in the bunker. But they survive and go to warn everyone.

Back at Der Riese the DG-2 project is working while the eleporters aren't. Maxis makes a series of tapes littered around der Riese. For experiment 6 they use Maxis's daughter's (Samantha) dog called Fluffy. The experiment didn't work turning Fluffy into the first Hell Hound. Samantha wanders in and sees Fluffy and becomes upset. While Maxis tells her there is nothing they can do about Fluffy Maxis's assisstant, Edward (or Dr. Richtofen) shuts the door on them. As Fluffy kills them they are teleported when Edward turned on the power. Fluffy was pregnant and her offspring became the other Hell Hounds, the teleporters show why Hell Hounds can materialise out of no where. Maxis and Samanth's souls remain anywhere that had to do with the experiments trying to get revenge. Maxis sais double points and max ammo etc and 'fetch me their souls' at the beginning of Hell Hound rounds while Samantha giggles when you get her teddy in the weapon box, when you throw the monkey bomb in the furnace or play hide-and-seek.

After when element - 115 supplies are low and Maxis was dead they cancelled the teleporter experiments and worked on the Wunderwafe in Verruckt. They started experimenting on the zombies behavior and it got crammed so Richtofen moved to Shi no Numa to continue research for the DG-2. There was a mass zombie outbreak in Verruckt killing everyone except an American called Peter. His hand was ripped to shreds by a zombie as he tried to activate the power which is still on the switch. He escaped with his life. He tried contacting Richtofen, in Shi no Numa in an Easter egg you can hear him.

He eventually arrives at Shi no Numa but he is driven crazy and hangs himself in the spawn room. You can tell it's Peter because of the missing arm. They send three super soldiers to Shi no Numa to make sure the project survives: Dempsey, Nikolai and Takeo. Richtofen made the zipline so he could transport experiments from the main building to his quarters. Zombies break out there but with experiments finished they go back to der Riese where they try and track down more 115. Once they obtain some more and develop it, it could be the key to exterminating the zombies for good. But in one of Dr. Maxis's tapes he sais that supplies at der Riese are low and that the Americans have a supply in a Nevada base (refering of course to Area 51) where the conclusion to zombies will take place in Map Pack 4 which will be relesed probably by the end of September.