It was the beginning of a new adventure in a new country: the 16-year-old was due to start Year 10 as an international student at Strathmore Secondary College, in the northern suburbs of Melbourne.

As they loaded their bags onto the airport security scanner, in the early hours of July 9, seven or eight men in plain clothes appeared. Without warning, they pounced on father and son and locked their arms behind their backs. They were dragged out, separated, and thrown into two waiting vans.

"I started to scream but one of the men put his hand over my mouth," Bao said in a phone interview. "Don't worry about giving a reason, they didn't even produce any identification before taking us away."

Around the same time, Bao's mother, prominent human rights lawyer Wang Yu, was at home in her apartment when the electricity and internet went out.

In a series of text messages to a group of fellow lawyers, she described hearing muffled voices outside the door, and the sound of someone trying to pick the lock.

"I looked outside through the peephole but it was all dark," she texted.

She tried calling her husband, and then her son. Neither answered.

Wang and her husband Bao Longjun have not been heard from since. They are among at least 261 rights lawyers, activists and law firm staff that have been detained or questioned by Chinese authorities in recent weeks in a coordinated crackdown spanning 19 provinces that has both shocked and outraged international rights groups and foreign governments.

It comes amid a broader suppression of civil society under President Xi Jinping , which has targeted intellectuals, activists, artists, lawyers, journalists and non-governmental organisations.

State media have described the crackdown as an operation to "smash a major criminal gang" that was "seriously disturbing social order".

At least 15 remain in detention, according to the Hong Kong-based China Human Rights Lawyers Concern Group, while another six are missing.

In a statement last month, the Australian government said it was concerned by the detentions, and that freedom of expression and peaceful assembly were guaranteed under China's constitution.

"We urge China to release all those detained for peacefully exercising these rights, or for lawfully defending others that have been detained for exercising these rights," the Department of Foreign Affairs and Trade said.

The younger Bao was taken to a hotel in Tianjin where he was held for two days, unable to make contact with the outside world. He has since been taken to Inner Mongolia, where he is staying with his grandmother while being monitored by police. His passport has been confiscated, and his hopes of studying in Australia indefinitely put on hold.

"I was happily preparing to go to Australia to start my studies," he said. "For something like this to happen, it's like falling to hell from heaven."

Strathmore Secondary College principal Jill English said she had been expecting Bao to start about two weeks ago for the start of term three, but he never arrived and no one at the school was told why.
"We were expecting the student to start with us at the beginning of term," Ms English said.

"He didn't arrive. We have not received any official communication. Beyond that, I have no more information."

Barring the 16-year-old son from leaving mainland China, rights groups say, is part of a cynical but common ploy to obtain leverage over detainees like Wang, for example, to coerce them into a confession.

"To a lawyer, a strident human rights defender, their family is the most direct way to threaten and blackmail them," fellow rights lawyer and close friend Chen Jiangang says. "Wang Yu, and other lawyers, can be extremely resilient as individuals, to the point they don't worry about their own personal safety. But once you involve their children, their elderly parents, they will feel like their heart is in a bind."

Ms Wang has gained a reputation for accepting prickly cases, including defending the five feminists who were arrested in March for organising a campaign against sexual harassment on International Women's Day.

She also represented prominent Uighur scholar and rights activist Ilham Tohti , before authorities forced her to give up the case. Mr Tohti was sentenced to life in prison on separatism charges last year.

The systematic targeting of intellectuals, lawyers and activists in China under Xi Jinping has had a distinct chilling effect on civil society and the freedom of expression. But there are also signs that the sustained crackdown has had a galvanising effect among the rights lawyers movement.

"My parents are honourable people who fight for justice," Bao said, adding he planned to study law when he finished high school.

with Nick Toscano