The legend of Mata Hari is well-documented. Code named 'Agent H-21, Mata Hari was accused of being a German double agent after the French secret service intercepted what they believed to be an incriminating message. An unpresented cheque and a container of 'invisible ink' were discovered in her hotel room and that evidence was enough for the French. She was executed. Her explanation was that the cheque was for services to German officers and the ‘ink' a common disinfectant that she used as a contraceptive. In hindsight, there was almost no evidence against her.
A turning point in the story of Mata Hari was the time she spent at the Grand Hotel of the Baths, Vittel. Holed up with her Russian lover. Vadime who had returned wounded from the front, she was blissfully hoppy-unaware of the she aroused. One guest later testified against her, "I smelled right away an adventuress." Another guest said, when questioned: "I became aware that this person had inflamed the masculine element at the hotel… I noticed that she was of a certain age, and that she had the air of a person who used morphine or cocaine... a schemer... one of the cosmopolitan women that one saw in spa towns before the war."
Pat Shipman, in her biography Femme Fatale, states that those who accused Mata Hari believed she was guilty simply because she slept with men and travelled widely in wartime. Such a woman, in their eyes, must be a spy.