The First World War took the lives of countless soldiers on the front line. But one man in Paris too old for combat saw this as an opportunity. Henri Landru targeted the lonely and vulnerable women left behind by the war. He seduced them with promises of marriage and lured them to houses outside Paris where the women vanished. With the police uninterested in investigating the disappearances, two women took it upon themselves to pursue Landru. This episode tells their story. How they tirelessly gathered evidence against the killer. How they pestered the authorities to investigate. And how they made sure Landru finally faced justice for his crimes.