In a Carmelite monastery on the outskirts of Los Angeles, life has continued virtually unchanged for centuries. Here, Sister John of the Cross lives in the service of God. She is the only nun who experiences visions and is regarded by the others as a spiritual master. But Sister John's is also plagued by powerful headaches and when a doctor reveals that they may be dangerous, she faces a devastating choice. Is this grace merely an illness and will a 'cure' mean the end of her illuminations and a soul dry and searching?