New York – one of the greatest cities on 21st century Earth... But what's going on in the Museum? And is that really a Woolly Mammoth rampaging down Broadway? An ordinary day becomes a time of terror, as Ice Age creatures come back to life, and the Doctor and Amy meet a new and deadly enemy. The vicious Army of the Vykoid are armed to the teeth and determined to enslave the human race. Even though they're only seven centimetres high. But as time starts to run out, who can she trust? And how far will she have to go to free New York from the Forgotten Army?