The plan was a simple one.

We'd arranged to meet a woman in her village in China's central Hunan Province and to then travel with her by train to Beijing, filming as we went.

But we never did get to meet our interviewee.

The story we ended up with, however, reveals more about the exercise of power in China than any interview ever could.

It is one that involves violence, intimidation and a forced confession - my first in my long reporting experience in China - in which I found myself apologising for "behaviour causing a bad impact" and for trying to conduct an "illegal interview".

Yang Linghua was planning to take the train to Beijing because she is what's known in China as a "petitioner".

Every year, many tens of thousands of Chinese people - denied the possibility of obtaining any justice through the local Communist Party run courts - head to the capital, taking their grievances to the "State Bureau of Letters and Calls".

Corruption cases, land-grabs, local government malfeasance, medical negligence, police brutality, unfair dismissal - all are documented in the bundles of papers - the petitions - they carry with them.

The system is also Communist Party run, of course, and the chances of success are tiny.

But for many, it's the only chance they've got, and they often continue to petition, in vain, for years.
Image caption The BBC interviewed Yang Quinghua, sister of Yang Linghua, three years ago

Allegations of brutality

Just like Yang Linghua's family.

The BBC interviewed her sister, Yang Qinghua, three years ago on a petitioning trip to Beijing.

The women allege that their land was stolen from them and their father, in the ensuing dispute, was beaten so badly he eventually died.

But there's a particular reason Ms Yang was trying to reach Beijing this week.

On Sunday, China begins its annual parliamentary session, The National People's Congress (NPC).

The event is like a magnet for petitioners who hope to use the grand occasion to promote their cause.

Beijing, though, has other ideas.

It would rather keep this ragged army of the dispossessed away from its carefully choreographed piece of political theatre and so provincial officials the length and breadth of the land, are tasked with stopping petitioners making the journey.

We knew that Ms Yang's sister and mother had already been placed under unofficial house arrest.

But as she herself had never been to Beijing to petition before, she felt she would be free from suspicion and, at the very least, able to board a train.

She was wrong.

As soon as we arrived in Yang Linghua's village it was clear they were expecting us.

The road to her house was blocked by a large group of people and, within a few minutes, they'd assaulted us and smashed all of our cameras.

While such violence can be part of the risk faced by foreign reporters in China, what happened next is more unusual.

After we left the village, we were chased down and had our car surrounded by a group of about 20 thugs.

They were then joined by some uniformed police officers and two officials from the local foreign affairs office, and under the threat of further violence, we were made to delete some of our footage and forced to sign the confession.

It was a very one-sided negotiation, but it at least gave us a way out - a luxury denied to the petitioners who find themselves on the receiving end of similar intimidation and abuse.

A video sent to us by Yang Linghua's sister shows her being detained by some of the same people who threatened us.

Warnings not to travel

In the course of researching this story we spoke to one woman, now in her seventies, who has been petitioning since 1988 for a longer prison sentence for her husband's murderer.

She told us that every year during the National People's Congress she is put under house arrest for 10 days.

A man we contacted, petitioning over the abduction of his son, had been warned not to travel this week.

He went ahead and booked his tickets anyway but was prevented from boarding the train in Guangdong Province.

Even for those who do make it to Beijing, the threat of being caught remains.

Outside the petitioning office this week, hundreds of "interceptors" have gathered, the squads of goons sent from each province to search out and cajole or coerce their petitioners to return home.

Of course, many petitioners do still make it and are able to lodge their claims, particularly first-timers who are not yet known to the system.

But the irony is, the harder China works to stem the flow during its national parliament, the more incentive there is for people to come.

Most petitioners are not so naive as to believe they'll be able to get anywhere near the senior officials attending the parliament.

But the desperation of their own provincial governments to catch them gives those who make it to Beijing a certain leverage.

Ignored all year round, often by the same officials they're petitioning against, they suddenly find themselves on the receiving end of offers to negotiate.

One petitioner showed us the text message exchanges she has had with the interceptors trying to track her down, with one even offering to take her on holiday. Anything to get her out of Beijing.

We have heard nothing from Yang Linghua or her family since they disappeared.

We have asked government officials in Beijing whether they can provide an assurance that they are safe and well.

Meanwhile, on the eve of China's parliamentary gathering, many of its citizens - often those, it could be argued, who are most in need of parliamentary representation - face similar abuse.

And despite having signed that confession I make no apology for trying to interview them.