Greatfall: A Silo Novel is a dark new tale in the world of Wool, Hugh Howey’s beloved post-apocalyptic novel. What happens when a silo goes dark? Maya has been sent to Silo 23 to investigate. Disconnected from the grid, Silo 23 appears to be dead, rotted from within. But what Maya finds when she opens the hatch is a silo that is anything but deceased. Unplugged from the outside world and its sister silos, Silo 23 has mutated into something unexpected and far more horrifying than Maya could have anticipated.