BEIJING // Peng Haiyang can remember the exact time of day she realised her young son had disappeared: 5.50pm.
She was preparing dinner inside her hairdressing salon in Dongguan, in southern China's Guangdong province, and Zhu Jie, then nearly 5 years old, was playing in the street.
But when Ms Peng went to check on her son that evening in May 2008, he wasn't there.
"I started yelling his name and looked up and down the whole street. Every child was inside their home so he couldn't have been playing with anyone else. Then I suddenly realised he had been abducted," she said.
Nearly four years later, Jie, described by his mother as skinny and with big eyes, is still missing. He is one among what are thought to be thousands of boys stolen each year from their families.
In a country that places limits on the number of children in each family, some couples without a son are prepared to take another person's child - even if they have been kidnapped.
In many rural areas, there remains a strong preference for boys, and the stigma attached to those who lack a male heir drives many to pay gangs who steal them.
The price, which is said to be about US$3,000 (Dh11,000), is many times the amount paid in China for girls. But it is still less than the fines typically levied when a couple exceeds the quota of children they are allowed. Buying a son can be cheaper than trying to produce one's own.
Hundreds of children have been reported missing from fast-growing urban areas such as Dongguan in China's southern manufacturing belt, possibly taken to serve the demand for sons in more traditional rural communities.
Dongguan is home to millions who, like Ms Peng, 37, and her husband Zhu Daolin, a 39-year-old driver, both originally from Hunan province further north, have travelled in search of work.
Advocacy groups said such migrant couples are "the most vulnerable group" when it comes to child abductions.
"They don't have the resources to look after their children," said Geoffrey Crothall from the Hong Kong-based organisation China Labour Bulletin. "If they are bringing the child to the city, both parents are probably working 12 hours a day. It's very difficult for these parents to provide adequate supervision."
Reports indicate gangs also prefer to take the children of migrant families because their weaker ties to the local area mean police are less inclined to investigate.
Determining the number of children stolen each year is difficult. According to China's official Xinhua news agency, police rescued nearly 9,000 children last year, as well as more than 15,000 abducted women, after uncovering more than 3,000 human trafficking gangs.
Families often say police are reluctant to even open a missing person's case, so government statistics might underestimate the total number of children taken. Unconfirmed media reports have put the figure as high as 20,000.
The past four years have seen Ms Peng try countless ways to track down her son. She travelled to Sichuan province when a man there said a boy similar to Zhu Jie had been seen, but she said local police refused to help.
With a group of other parents of missing children, she went to Beijing in 2008 to urge the government to pressure local authorities to investigate child abduction cases. Yet the parents were unable to meet officials.
Now she concentrates on posting about her missing son on microblogs and Chinese-language websites such as Baby Come Home and the China Missing Persons Database, which has the details of hundreds of missing children.
Other families have similar stories of heartache.
It is almost five years since Yang Chunyan's son, Zhan Yicheng, failed to return from school.
Feeling ill while pregnant with her second son, Ms Yang, now 30, decided that day not to meet her six-year-old at the school. She was sure he would be safe to walk the 300 metres home in a village near Huizhou city in Guangdong province, where the family had moved.
When Yicheng failed to arrive, it triggered a nightmare of fruitless searches, bureaucratic indifference, and fraud by people trying to extort money. Initially, police refused to open a missing person's case because Yicheng had not been gone for 24 hours.
Attempts to raise awareness through local newspapers brought hopes that were cruelly dashed. Some called and said if Ms Yang bought them telephone credits, they would lead her to her son. Others promised to arrange for Ms Yang to meet her child if she transferred money to their bank accounts.
"I was so eager, so anxious to find my son, I complied, but every time, when I showed up, it was in vain. Nobody was there," she said.
Searches through the local countryside also came to nothing. Ms Yang's husband, Zhan Dexin, a shopkeeper, even visited gambling dens in the hope of finding child-trafficking gangs.
Now Ms Yang also pins her hopes on the internet, regularly updating the entry about her son on Baby Come Home and setting up an instant messaging account to post details about him.
"Every time I see a boy of my son's age, I can't help crying. I also feel very guilty, because it was my fault my son went missing," said Ms Yang. "Sometimes I feel like I want to give up on life, but my parents say he will come back one day."
Back in Dongguan, Ms Peng, who with her husband also has a daughter, Zhu Ting, 14, likewise believes that one day she may be reunited with her son, who would now be eight years old.
"I still live in Dongguan. I don't want to move. I am waiting. I am waiting for my son. I hope somebody will let me know that my son is still alive somewhere," she said.
