For centuries, the people of Motus have tunneled through the rock in search of the resources they needed to survive. Until Corun, armed with his late father's pickaxe, uncovers an unfamiliar ore in the underground city's path.

Far from the riches he hoped for, an appraiser identifies the ore as slag from the furnace, rock long ago stripped of its useful water and oxygen. It can only mean one thing.

They've been moving in circles.

Faced with the prospect of retracing their steps or descending to more inhospitable depths, the city's laborers go on strike. Corun, inspired by an outspoken Ascensionist, believes their only hope lies on the rumored Surface. But to get there, they will have to contend with cold rock, thin air, and a jaded board member impeding their progress at every turn. And what they find will test their wits and resolve and make them question everything they were ever told.

Reminiscent of Wool and City of Ember, with an adult, hard sci-fi twist, MOTUS explores the travails and triumphs of a people determined to carve an existence out of cold and unforgiving stone.