When beautiful women start turning up dead in Paris's Seine River, D'Eon -- the brother of one of the victims -- is determined to find the killer. It helps that he's inhabited by his sister's spirit. Set in pre-Revolutionary France, this anime series takes its inspiration from the real-life character of the same name -- a diplomat, writer, spy and Freemason who lived the first half of his life as a man and the second half as a woman.