Mary’s living the dream when she marries her running partner, Matt. They celebrate Christmas, making plans to run the ultimate footrace through wild South Africa. Then in a horrific flash, everything’s gone—her husband, her ability to breathe without oxygen support, her purpose for living. One year later, as she grieves by Matt’s grave, Mary takes out her anger on God. A man standing nearby sees her pain, and shares his own tragic story of loss. Once a doctor in Africa, he escaped before civil war annihilated his entire hometown. Now he’s known as ‘Coffin’, the grave digger, and he offers his help. Despite her doubts, Mary agrees to meet Coffin for coaching and physical training. Soon she’s running again, only to suffer a deadly collapse. Believing that Mary is dead, Coffin returns to his African home. Only one building remains, an icon-filled Christian chapel, where he treats the sick. Months later, Mary walks into the chapel. Shocked, Coffin thinks he’s seeing a ghost. But Mary continues to greet him each morning until Coffin believes again. Healed, and ready to enter The Furnace’s week-long marathon, Mary tries to survive wild animals, and extreme conditions. Then encounters with a scorpion, a lion, and another runner turn up the heat on her consciousness. Ready to die, Mary sheds the last relic of her heartbreaking loss. But will she make it out of The Furnace?