4400 overlooked, undervalued, or otherwise marginalized people who vanished without a trace over the last hundred years are all returned in an instant, having not aged a day and with no memory of what happened to them. As the government races to analyze the potential threat and contain the story, the 4400 themselves must grapple with the fact that they've been returned with a few "upgrades", and the increasing likelihood that they were all brought back now for a specific reason.

Batman raises the stakes in his war on crime. With the help of Lt. Jim Gordon and District Attorney Harvey Dent, Batman sets out to dismantle the remaining criminal organizations that plague the streets. The partnership proves to be effective, but they soon find themselves prey to a reign of chaos unleashed by a rising criminal mastermind known to the terrified citizens of Gotham as the Joker.