The movie starts with a group of soldiers transporting something out of Area 51 and their truck crashes with a car. The payload that the soldiers are carrying is compromised because of the crash and gets unlocked. One of the soldiers then talks to the base about the crash and the base commands him to take anyone alive away from the payload. It turns out that the payload has a zombie in it! Watch the trailer:
The whole city of Las Vegas turns into a zombie war zone after this incident. The government makes it a quarantine zone. One casino owner asks a man to gather his team for one last heist. The casino owner has $500 million cash in his safe, and obviously, he wants it. Hence a group of people venture into the war zone for one last heist.