Empress Wu Zetian (624-705 AD) was the only woman to be the sovereign ruler of imperial China. A teenage concubine of the Tang Emperor Taizong, she seduced his son while the emperor lay dying. Recalled from a nunnery as part of an intricate court power-game, she caused the deaths of two lady rivals, before securing her enthronement as the Emperor Gaozong's consort. She ruled in the name of her husband and two eldest sons, presiding over the pinnacle of the Silk Road, before proclaiming herself the founder of a new dynasty. Worshipped as the Sage Mother of Mankind and reviled as the Treacherous Fox, she was deposed aged 79, after angry courtiers murdered her two young lovers. The subject of countless books, plays and films, Empress Wu remains a feminist icon and a bugbear of Chinese conservatism. Jonathan Clements weighs the evidence of her life and legacy: so charismatic that she could rise from nothing to the height of medieval power, so hated that her own children left her tombstone blank.