I have been working on this image, off and on, for a couple of months. Here is the present state. It is of St. Philomena, a martyr during the reign of Diocletian. After refusing his advances and refusing to offer sacrifice to the Roman gods, this young Christian girl was tortured by him in various ways. This painting is where she is tied with a rope around her neck and anchor other other end of a rope and thrown into the Tiber River.
No sooner had she gone under when she suddenly rose up out of the water, free of the rope and completely dry. The roman pagans who were present cried out for Joy for her and were baptized. Diocletian, furious, had her shot with arrows, but to no avail. The next day she was healed of all wounds, so he had arrow tips made red hot with fire and shot at her, but the arrows turned course and struck six of the archers that shot them. Finally, she was beheaded. More of her account here: http://www.philomena.us/saint-2/history-saint-philomena/story-saint-philomena/