Gilles de Rais fought alongside Joan of Arc, rose to Marshal of France, and then confessed to torturing and killing dozens of children on his estates in Brittany. This film traces that split biography, from his military record in the Hundred Years' War to the alchemical experiments and financial ruin that followed his fall from royal favor. It lays out the 1440 trial in Nantes, where church and secular courts heard testimony from servants and grieving parents, and where Gilles himself eventually admitted to the killings under threat of excommunication. The film weighs the case historians still argue over: whether the confession was genuine, coerced, or shaped by political rivals who wanted his lands. Contemporary accounts, trial records, and the physical remains of his castles at Tiffauges and Machecoul anchor the narrative in documented fact rather than legend, even as it acknowledges how quickly Gilles de Rais became folklore, feeding later stories like Bluebeard. It stays with the historical record rather than the myth.