In 1874, at the age of 25, she desired to marry an older lawyer who was not to her mother Louise's liking; she argued that her daughter could not marry a "penniless lawyer".[3] Her disapproving mother, angered by her daughter's defiance, locked her in a tiny, dark room in the attic of their home, where she kept her secluded for 25 years. Louise Monnier and her brother Marcel continued on with their daily lives, pretending to mourn Blanche's disappearance. None of her friends knew where she was, and the lawyer who she wished to marry died unexpectedly in 1885.