The fit and fierce Mary Harris could not have been happier, marrying her running partner, Matt. Until a truck hits their car. A year later, Mary is all but incapacitated by both the loss of her husband, and the use of one lung. Forced to wheel around an oxygen cylinder, Mary no longer feels the joy that running once brought her. A grave digger, named Coffin (a nickname easier to say than his African name), notices the haunted, angry woman. He shares with her the story of his own loss, and his qualification as a doctor. Mary agrees to let this wise gravedigger train her, despite her stubborn outlook. The Furnace is the extraordinary story of just what it takes to heal yourself, and restore your faith. For Mary, it's an ultra-marathon through the harsh African bush-veld.