Dai Xiaolei last saw her son in 2014 when he was 17 months old and living with her Chinese in-laws outside Beijing.
Her marriage was crumbling and as relations with her husband's family worsened, they blocked her from entering the house and taking him back to her home in Beijing, she said.
"The last time I saw my son was at the end of this alley. It's almost like a fortress," Dai, 37, said outside the home of her former in-laws in Baoding, 156 km from Beijing.