The final book in the bestselling 20 Minute Series! The threat to Earth has never been more real, and as the fate of humanity hangs in the balance, there is nowhere on the planet that is safe. London, like every other major city, has fallen into a state of disorder, and its inhabitants are having to spend almost as much time worrying about the dangers on the ground as they are about the dangers in the sky. As the clock ticks down until the moment of reckoning, it’s every man or woman for themselves, and several characters decide to take shelter in the only place they can. They head underground... They go back to where it all began…