Subterrania

We did not kill the planet, we made it nearly uninhabitable.

The few surviving societies of humanity begin to recover from an extinction level threat, but as their numbers grow they realize there isn't enough land to support them. In an attempt to solve this problem the "Expansion Project" is created. The Expansion Project is an attempt to rectify the population density issue by dispersing their people within livable underground spaces. With tons of materials harvested and living space growing every day, thus far, the project has been a solid success.
Young excavator and engineer Peter McKenna is going about his business as usual. Leaving the towering streets of Littleton, New Colorado, as he and his co-workers descend fifteen kilometers down the mouth of the mine. Together they carve deeper and deeper into the Earth's crust only to discover what secrets lie within the deep biosphere unseen by human eyes.