Life-and-death battle for Sarah
While her Shortland Street character Sarah Potts faces the biggest challenge of her career - an infectious virus that she cannot diagnose - Amanda Billing ponders how she would handle such a crisis.
"I've dealt with adversity in the past and I will again," Amanda says. "We've all had setbacks in our life and at the end of the day there have been times when I've been passive in the face of those setbacks.
"But there have been other times when they've brought out the best in me. I think that's actually what this situation does - it brings out the best in Sarah and I really enjoyed that."
Thankfully, Billing does not have to deal with the high-stakes challenges that Sarah does on a daily basis, although she says this time it is tougher than usual for the diagnostic expert.
"She's in the worst position for a doctor to be in, which is where she can't heal people and that is the hard thing," Billing says.
"It's just feeling powerless, feeling helpless, the uncertainty of it and the literally life-and-death nature of it. If people show up she can't make them better, she doesn't know how to make them better and that's a horrible feeling."
Sarah's crusade to find a cure could also have had dire consequences for her relationship, says Ben Mitchell, who plays her long-term partner TK Samuels.
"She's a medical professional trying to be a scientist," Mitchell says. "That actually pisses him off to tell the truth.
"She's a mother; she should be there spending time with her family. She's got MS herself and she's not really taking care of herself...
"Then he starts to realise that she's got this obsessive compulsive thing to do it and that's her nature and he loves that about her too."
Billing, who has played the tenacious doctor for almost 10 years, admires Sarah's persistence.
"Tenacity, that's a good word (for it)," Billing says. "I think she's probably more like that as a rule than I am. Having played someone for such a long time it's really interesting when their positive characteristics come out like this. Like being able to see humour in a difficult situation or not giving up or loving someone unconditionally."
Fans of the couple will be pleased to see that out of a grave situation comes a commitment between TK and Sarah in the form of a proposal.
"Their relationship changes because of their involvement in this situation," Billing says. "That tenacity can be really annoying for (TK) but he knows that it results in good things for other people."
Of the proposal, Mitchell respects his character's take-charge attitude.
"I relate to his masculine focus," Mitchell says. "He's explosive, he's intense, he's deep, he's devoted. He's not ambiguous... He's black and white. If he doesn't like you he'll tell you... I love these qualities... Plus he gets to have a lot of good-looking girls with him. That's the boy in me, the little kid goes, 'I really like the hot girls I have to kiss everyday'."
While it may finally be happily ever after for Sarah and TK, the problem of the contagious virus remains. Can Sarah make a diagnosis before it is too late?
"The thing about this storyline is that it's the hero's journey," Billing says. "She's always been that sort of character where she goes out in the world and she's got a problem to solve and she conquers or not as the case may be...
"I think we like that story as human beings because it's inspiring and reminds us that we face these challenges in our own life."
The last time Billing faced such a professional challenge she was tackling theatre, after many years on TV. Last November, Billing played Roxie Hart in Auckland Theatre Company's Chicago opposite Lucy Lawless and Shane Cortese.
"I am constantly saying to myself 'Am I ready? I don't know if I can do this'," Billing says. "I was supported by everyone that I was working with and that's a crucial part of it as well and that's central to Sarah's story too. She has to trust herself.