At 14 years old, she was sent by her mother to live with a successful businessman in Beijing, who was supposed to serve as her caretaker and guardian. Instead, over the course of several years, she says, he repeatedly raped her and held her in his home against her will.

Now 18, the young woman, using the pseudonym Xingxing, has gone public with her account of abuse. Her story, published in the Chinese news media in recent days, has become one of the most widely discussed topics in China, unleashing a wave of anger about the country’s patriarchal culture and the authorities’ reluctance to intervene in cases of sexual abuse.

The episode has become a pivotal test for China’s small but spirited #MeToo movement, which has gained traction in recent years despite the ruling Communist Party’s strict limits on activism and its tight control over the courts.

The man at the center of the case is Bao Yuming, a lawyer who studied in the United States and has advised some of China’s most prominent companies, including ZTE, the telecommunications giant. Mr. Bao, who is in his late 40s, has acknowledged that he had a close relationship with Xingxing but has denied any wrongdoing.