Years after an apocalyptic event, a powerful AI-driven supercomputer called "The Great C" rules over the remnants of humanity. Each year, the nearby village is forced to send a young person on a pilgrimage to appease the mysterious machine, a journey from which no one ever returns. The Great C follows Clare, a young woman who finds her life upended when her fiancé is summoned for this year's pilgrimage. Leaving the safe confines of her village, Clare must decide whether to accept the rules of her harsh society or fight against the oppressive powers that created it.