The fourth season of Torchwood explores this universe: One day, nobody dies. All across the world, nobody dies. And then the next day, and the next, and the next, people keep aging -- they get hurt and sick -- but they never die. The result: a population boom, overnight.
With all the extra people, resources are finite. It’s said that in four month's time, the human race will cease to be viable. But this can’t be a natural event – someone’s got to be behind it. It’s a race against time as C.I.A. agent Rex Matheson investigates a global conspiracy. The answers lie within an old, secret British institute. As Rex keeps asking “What is Torchwood?", he’s drawn into a world of adventure, and a threat to change what it means to be human, forever.