Marie Arnoux was a young Haitian woman who lived in Port-au-Prince and was hired as a guide to Indiana Jones and George McHale when they needed to travel to Zile Muri-yo in 1943. She was a tall, beautiful woman, with even features, smooth skin, and lovely black hair. She had a younger brother, Alain Arnoux, who resembled her, and a cousin, André. She was also related to Boukman, and was secretly a mambo, or voodoo priestess, like her mother had been. She was fluent in French, Creole, English, and the dialect spoken on Zile Muri-yo.
In the late 1930s, Arnoux attended a woman's college in New York for four years, majoring in history and getting a minor in comparative religions. While there, she became a Brooklyn Dodgers fan, even watching Waite Hoyt's last game in 1938.
In the summer of 1943, Arnoux was hired by Indiana Jones and George McHale to guide them to Zile Muri-yo to find the Heart of Darkness. She quickly surprised Jones by recognizing that he was an American, and that she was college educated and knew that the city was full of spies like Joe Edmonds. Agreeing to help them, she first sent them with her brother to stay at Josette's rooms, away from spy-filled hotels,
The next day, her brother dropped her and the two foreigners off in Terre Rouge, where André ferried them across to Zile Muri-yo in his fishing boat. She guided them to the island's store, where she hired Batiste and some porters through Père Ours, while Jones and McHale purchased provisions and ammunition for the expedition. She then took her customers to Efreye Village for the night, where she introduced them to Batiste, and left to bathe at the village's bathhouse. She rejoined them at the campfire, and questioned Batiste about the route to take to the cursed place.
- Indiana Jones and the Army of the Dead (First appearance)