'Let me tell you a story. Long ago, in the frozen Arctic wastes, an alien army landed. Only now, 10,000 years later, it isn't a story. And the army is ready to attack.' 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 the Doctor and Amy meet a new and deadly enemy. The vicious Army of the Vykoid are armed to the teeth and determined to enslav