November 9th, 1965. New York City is plunged into darkness, a taxi driver has bad dreams, and an invisible spacecraft hovers ominously above the skyline. As an extra-terrestrial disease sweeps the populace, Amy and Rory must sabotage the city's water supply to slow the spread of infection, and a dying Doctor holds another man's life in his hands. With the death toll rising, and his companions stalked through the streets by alien businessmen, the Doctor is forced to make a terrible decision. How far must he go to save his friends?