From the Introduction
The year is 2052. 90% of the Earth's surface is covered in ocean water. The ocean isn't the only thing that has grown out of control. The population on Earth has nearly doubled in the last 20 years. Forced inland by the encroaching sea, mankind constructed towering structures in an attempt to find new spaces. But it isn't enough. You can only build so high, after all. Now, the only way to go is down. And, that's where you come in. They call you Diggers. You work for MegaCore, the first company to begin the downward expansion of the human race.
It's been just over a year since MegaCore started construction under the Gibson Desert in Australia. Digging into the Earth's crust using massive lasers, they've gotten over ten miles down and spread out twice that in either direction, setting up livable spaces and forward camps. Two months ago they made an amazing, yet unsettling discovery. Veteran workers, used to life below and unshakable, have been called in to crew the next, unanticipated, part of the excursion.