There are lines in the script that you’d swear were torn from a B-grade soap.

But this is not an episode of Revenge or Dynasty, it’s the bold portrayal of the romance between mining magnate Lang Hancock and Filipino housemaid Rose Lacson and how it ripped the Hancock family apart.

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The two-part drama is a work of rare creative synergy, deftly written and directed and perfectly cast with Sam Neill as Lang, Mandy McElhinney as daughter Gina, and Peta Sergeant stealing the show with an extraordinary take on Rose.

There’s love, betrayal, lust – even a bit of toe-sucking, for heaven’s sake – so it’s easy to see why Sergeant was panic-stricken about bringing authenticity to her role.

Peter Sergeant as Rose. Photo: Nine

Half-way through filming, Sergeant was called on to play a scene where Rose “entertained” Lang and dinner party guests with a rendition of ‘Love is a Battlefield’. It’s car-crash stuff.

So overcome was Sergeant with fear that she couldn’t live up to expectations in the role that she experienced something of a meltdown.

“Rose is so much fun, a crack-up who draws electricity – she’s a lightning rod,” Sergeant says.

“She’s vibrant and magnetic. The hardest thing for me was trying to reconstruct the physical and vocal qualities of a living person. But you can’t be controlled in trying to play her, you just can’t, because her essence is so mercurial, loose, dangerous and out of control.”

To prepare for the karaoke scene, Sergeant retreated to her hotel room, put a DVD of Rose on the TV, took a hairbrush in hand and sashayed about the room.

“I spent long nights, til the wee hours, with that brush, practising the song,” Sergeant explains.

“I got to set that day (to shoot the scene) and I was an absolute wreck, so nervous I couldn’t keep food down.

“It was terrifying. My body was evacuating. I think you can work out what that means. I was in adrenal overload and I was in the toilet every 10 minutes. I had been trying to slim down because Rose is a lot smaller than me. If only I’d known,” Sergeant adds with a laugh, “that the best diet in the world is fear”!

“We went for the first take and after it the director Mark Joffe called ‘fantastic’. Claudia Karvan (producer) asked me if I’d secretly used a choreographer for the scene. I just said, ‘no, it was me and a hair brush in my apartment and lots of tears of terror.

“From that point on, I gave myself permission to let it all (anxiety) go and the role became like a big, fun waterslide to ride out. It was such a gift.”

Mandy McElhinney as Gina Rinehart. Photo: Nine

Lang Hancock discovered the world’s biggest iron ore deposit in the Pilbara in 1952, but is equally renowned for his controversial relationship with Rose, which began soon after the death of his wife Hope in 1983.

Gina was bitter her father allowed “gold digger” Rose into his life and even more appalled when the couple married.

In the early days of production, Sergeant had wanted to meet Rose. Once into filming, though, Sergeant felt that meeting her would be a bad idea. The actress believed seeing Rose in the flesh would leave her thinking she would never “get” Rose and that would undermine her performance.

Once that karaoke scene was in the can, Sergeant again changed tack.

“I really did want to meet Rose but that was no longer an option,” she says. “I’d been informed there had been threats of litigation and the lawyers said nobody can have contact with anybody.”

So how does Sergeant hope Rose responds to her portrayal?

“I had to let that thought go during filming because you can’t be thinking about that. It’s (Rose’s reaction) not within my control,” she says.

“Now, I’m nervous, I don’t know how they’ll react. I don’t want them to get hurt.”

House of Hancock, Sunday, 8.45pm, Channel 9