It's 5:15am on August 1 and a group of climate activists are congregated in the front room of Matilda Lane-Rose's Perth share house.

They're locked in tense deliberations about this morning's planned protest.

Nineteen-year-old Tilda has been psyching herself into doing this for months.

Four Corners has been with the group for two days but doesn't know where they are heading. It's understood it will be the first time Tilda will be doing something illegal.

"I feel like I've exhausted every other avenue, really. So this is the logical next step in my fight to pursue what matters to me," she says.

The activists are members of Disrupt Burrup Hub. Their protests are targeting Australia's largest oil and gas company, Woodside Energy, and its expansion on WA's Burrup Peninsula.

The peninsula is home to two vast gas plants and one of the most significant Indigenous rock art collections in the world.

This morning, though, the activists get some bad news. A member of their group was stopped by police and had a gun drawn on him while scouting the location of the protest.

"Are the cops going to be there when I arrive?" Tilda says.

She meditates, consults her boyfriend Nick, then announces her decision.

She's doing it.

The battle

The Burrup Hub is a critical flashpoint in the global battle against climate change.

Woodside believes it is crucial for the stability of international energy markets and Australia's transition to net zero. But over its lifetime it's estimated the hub will emit the equivalent of 24 coal-fired power stations operating for 50 years.

Woodside's former climate change adviser and lobbyist Alex Hillman told Four Corners:

He now works with the Australasian Centre for Corporate Responsibility.

Energy analyst Saul Kavonic says trying to stop new gas projects isn't the answer.

"We can't just look at our gas industry … and say it needs to shut tomorrow," he says.

"This sector is integral to Australia's economy and global civilisation."

He says the Burrup Hub will provide gas and jobs for Australia, as well as contributing to the budget surplus.

The activists, though, are pushing ahead — even if it means breaking the law in protest.

A few weeks earlier, Disrupt Burrup Hub held a recruitment event at a chic photography studio in West Perth.

"This month that we are in now is expected by scientists to be the hottest month recorded," one of the group's founders, 31-year-old former schoolteacher Gerard Mazza, told the small crowd.

Arts student Tilda agrees.

"We're barrelling towards a climate crisis at incredible speed."

She started out in activism at age 15, taking part in the School Strikes for Climate, but believes more drastic action is now needed.

Others might disagree, but she insists Disrupt Burrup Hub champions non-violent protest activity.

"We don't believe in actions that entail violence towards people. I don't want to harm another person. I don't want to injure them."

But they do believe in being prepared.

The rehearsal

The evening before the protest, 35-year-old mum-of-two Tahlia Stolarski is crouching over pots of yellow paint, holding a large, fluorescent water gun.

Next to her, Tilda looks frustrated. "I just cannot find the instructions," she says.

The toy's packaging promises it can rapid-fill 100 balloons in less than 60 seconds, but things aren't going to plan.

The Disrupt Burrup Hub activists have come to some old horse stables behind Tahlia's house to rehearse.

"I reckon the most important thing is to practice rather than to get everything 100 per cent ready at this very moment," says Jesse Noakes, 34, the group's co-founder and media adviser.

The protest is Tilda's brainchild; she'll play the lead role and Gerard and Nick will film and photograph her in action.

Tilda recites her moves: "6:00: playtime; 6:01: spray; 6:02: tip."

"The only thing you missed was 'deploy lights'," Jesse says.

"I will deploy the lights," Gerard says, grabbing a coffee cup as a stand-in for a spotlight.

Tilda spray-paints 'DISRUPT BURRUP HUB' on the wall and lobs yellow paint as Nick and Gerard pretend to film her.

She then slips a bike lock around her neck and attaches herself to a stake in the corner.

"And then … we'll do a piece to camera," Gerard says.

"Saying something profound, moving, brave, bold, intellectual," Tilda says.

The protest

It's the morning of the protest and the activists have moved to the outside of Tilda's house. But she's hit a snag.

"I f***in' locked myself out," she says, rummaging inside a yellow bucket.

"I don't have my car key … Shit."

She wakes her flatmate to come to the rescue, and Tilda, Nick, Gerard and Jesse pile into her $500 car.

Jesse turns the key, but it won't start.

"Just hold it, like, constantly," Tilda says. "And then it'll rev to life."

Soon they're on the freeway, hurtling towards an affluent suburb of Perth.

There's a nervous energy in the car. Tilda plays PJ Harvey's song Rid of Me on her iPhone and the sky turns from ink black to dark blue.

They pass the Woodside building.

Jesse says touchdown is in five minutes, right on sunrise.

Tilda breaks into nervous laughter, then asks: "Anyone have any final words?

"Bye, Tilda. Nice knowing you," she says, answering her own question.

The car turns into a suburban street.

"I'm gonna remember this day for the rest of my life," Tilda says.

They pull up outside a big house.

"She's home," Gerard says.

It's the home of Woodside Energy chief executive officer Meg O'Neill.

The police

Nick grabs the buckets as Tilda takes off her hoodie, exposing a Disrupt Burrup Hub T-shirt.

Gerard races up the driveway and drops a spotlight on the ground next to the front gate.

He doesn't realise the police are waiting.

He turns and runs as several armed officers emerge from the direction of the house.

"Police! Don't move! Don't move! DO NOT MOVE!"

Gerard, now halfway across the road, raises his arms in surrender.

"You're under arrest for trespassing," an officer says.

Tilda, barely out of the car, looks up bewildered.

"You're under arrest for suspicion of criminal damage," another officer says to her.

The two are marched up the driveway and stood against a wall as they are read their rights.

Jesse is also arrested.

Nick wanders to the other side of the road and watches.

Ms O'Neill appears briefly at an upstairs window and looks down on the scene. She lives at the house with her partner and daughter.

Over the next hour, more police arrive. There are more than a dozen officers on the street. It's no ordinary operation.

Tilda, Gerard and Jesse are bundled into police cars and driven away. They'll be charged with conspiracy to commit an indictable offence and will stay in custody overnight.

They're not alone. Four Corners can reveal climate activists across the country are being charged with serious offences in unprecedented numbers.

Records collected from major activist groups show that, since 2021, almost a hundred of their members have faced jail terms of two years or more. Prior to that, there were almost none.

This rise is likely a combination of an increase in protests and police activity.

In WA, the police's State Security Investigations Group (SSIG) is investigating at least two local climate activist groups, including Disrupt Burrup Hub. They usually deal with violent extremists and threats to state and national security.

If the SSIG officers were keeping an eye on the Disrupt Burrup Hub activists, "it's because of their previous behaviour," WA Police Force Assistant Commissioner Joanne McCabe told Four Corners.

She referenced a stink bomb protest at the Woodside headquarters in Perth in June that led to an evacuation of the building and people requiring hospitalisation. But when Four Corners requested more details, a WA Police spokesperson retracted the statement.

They said that while seven people had reported symptoms such as nausea, dizziness and breathing difficulties, they couldn't find anything confirming hospital attendance.

The raid

Tilda and the activists' protest triggers a media storm.

The same morning, Tahlia is at the house of another Disrupt Burrup Hub member when she reads remarks made by Ms O'Neill.

"Such acts by extremists should be condemned by anyone who respects the law and believes people should be safe to go about their business at home and at work."

Tahlia thinks about Ms O'Neill's comments and then says: "What about my kids feeling safe when they're adults?"

Four Corners is also criticised in the media for its presence at the protest.

The activists are shaken. They underestimated the level of police surveillance, and the three arrests were the worst-case scenario.

Tahlia's phone rings. It's the police. Six officers are waiting outside her house. If she doesn't return within the hour, she is told they will break in. It's the third time in four months she's been raided.

Tahlia was charged earlier this year with aggravated burglary for attempting to set off a stink bomb at a Woodside AGM. It's the most serious offence any climate activist has ever been charged with in WA and has a maximum penalty of 20 years.

She heads home and is arrested.

Police search her house and the old horse stables where they rehearsed, looking for evidence of this morning's protest. A female officer body searches Tahlia in her kitchen.

Midway through the raid, Tahlia's husband arrives with their children. They decide he should take them elsewhere so they're not frightened.

"They searched every room, including my kids' room," Tahlia says.

"I'm quite angry.

"I think that Woodside's influence in Western Australia in particular is really infringing on our rights."

The aftermath

In the days following the protest, Ms O'Neill says it left her "shaken, fearful and distressed".

"It does not matter if you are a member of the business community, a professional athlete or even a kid going about your business," she says.

"What happened … is an unacceptable escalation in activity by an extremist group which has absolutely no interest in engaging in respectful and constructive debate around Woodside's role in the transition to a lower-carbon world."

She takes out violence restraining orders against Tilda, Gerard, Jesse and another Disrupt Burrup Hub activist.

Four Corners asks Tilda if she believes she crossed ethical lines by choosing a private residence as the target for protest.

"I think no matter what we do, it's going to cross a line to some people," she says.

Ms O'Neill's comments, though, make her reflect on her tactics.

"You'd have to be very cold and callous to say, 'I don't care about her'. This action wasn't designed to strike terror onto Meg. It was designed to hold someone who's accountable for what's happening on the Burrup.

"You need to keep on escalating until real change is made."

Ms O'Neill declined several requests to be interviewed by Four Corners because of its presence at the protest.

Tilda's court case is ongoing. If found guilty, she could be sentenced to up to three years in prison.

Watch Four Corners: Escalation, tonight from 8.30pm on ABC TV and ABC iview.

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Credits

Story by Hagar Cohen - ABC Investigations, Mayeta Clark and Dylan Welch

Digital editing and production: Kate Sullivan

Graphics: Nicole Koncz