A pair of senior citizens travel Australia’s Outback in a camper, solving crimes while bickering and bantering.

That’s the set-up for AcornTV’s “Darby and Joan” which teams Bryan Brown (“The Thorn Birds”) and Greta Scacchi (“Presumed Innocent”) and begins S2 Monday.

For Scacchi, the series is due to how easily the duo click. Five years earlier they had co-starred in “Palm Beach” which was directed by Brown’s wife Rachel Ward (the couple met on “The Thorn Birds”).

“This is due to the chemistry we had onscreen in that film, and the fun that we had making it and working together. That planted this ‘Darby’ germ,” Scacchi, 64, said by phone from London’s West End where she’s currently onstage.

“It’s rare to get an invitation, and it’s rare that an actor has that authority, really, where he was proposing we work together again. It’s very gratifying.”

Filming each episode on various, often scenic locations is demanding. “The hours are difficult, the relentlessness of the schedule is difficult,” Scacchi conceded, “but the work itself is just fun and joyous.

“And to collaborate with Bryan again — we’re very compatible personalities. He’s got his very blunt, straightforward Australianness and I’m no good at guile and subterfuge.

“I’m much more comfortable when people are frank and open. He’s warm and friendly, and I like that.”

In S1 Joan, a retired London nurse, arrived in Australia to investigate her husband’s mysterious death. She met Darby, an ex-detective with lingering issues over his last case, when they literally crashed into each other on an Outback road and became travel companions.

In S2 Joan helps save, and then treat, a hit and run victim. Her nursing background offers a more commanding presence.

“In the first season, she was wrapped up in the emotional trauma that had just happened” — her husband’s death.

“In the second series, there’s hardly any sign of it. It’s as if she has found a new calling. And she’s enjoying herself.

“There’s a yin and yang about the two of them. I think she is more at ease than him — in that she’s able to express herself well. She’s able to shoot from the hip. She’s an absolute for the truth and honesty.

“He is in some ways more guarded. More reserved. He’s got an outer crust where he presents himself with confidence. But he’s harder to penetrate, really.

“And yes, she’s got the practical, single-mindedness of an experienced nurse ready to focus on what is priority in an emergency. But both,” she noted, “are very nosy.

“Of course, if they weren’t that nosy, then they would just drive on to the next town. But no, they’re both angels of justice and they share that desire to put things right.”

Season 2 of “Darby and Joan” streams on AcornTV Dec. 30