After “Chicago P.D.” and “Homicide: Life on the Street,” Jon Seda didn’t expect his career to go into a sinkhole.

That’s not even a figure of speech: His character is among those who fall in when a sizable chunk of Los Angeles literally opens up in “La Brea,” a NBC adventure drama series premiering Monday, Sept. 27. Those who are forced to take the plunge find themselves in primeval surroundings, while others who have remained above ground try to determine what happened and how to reunite with those they apparently have lost.

Natalie Zea (“Justified”), Eoin Macken (“The Night Shift”), Zyra Gorecki and Jack Martin play members of a family separated by the phenomenon, while Seda portrays an ex-Navy SEAL turned thoracic surgeon who’s thrust into the land beneath L.A. “I’ve been really fortunate in my career to play different types of characters,” the pleasant Seda reflects, “so when this opportunity came up, I knew it really was something different.

“I hadn’t been thinking about doing something like this, but it was something I could enjoy wholeheartedly. To me, it’s the epitome of a Hollywood project ... almost like watching a ‘Star Wars’ movie that takes you away on an adventure. I thought, ‘Wow! I definitely have to grab onto this.’ I lived in L.A. for about four years, but I was more worried about earthquakes. I never really thought about sinkholes.”

One of the ironies of “La Brea” is that while its setting is very American, it’s actually being filmed in Australia. Seda has worked there before – when he made HBO’s 2010 limited series “The Pacific” – and he says, “The landscape is amazing. It adds so much, especially since with ‘La Brea,’ you have the sinkhole and this crazy world that we find ourselves in. A lot of the same crew members worked on ‘The Pacific,’ so we’ve been doing a lot of reminiscing.”

Still, working in Australia means a long separation for Seda (who terms himself “an East Coast kind of guy”) from his U.S.-based family, underscored by the quarantining that’s required for international travel now.

“That’s the tough part,” Seda allows. “The pilot was filmed in Vancouver, and I thought even that was a stretch (distancewise). Then the pandemic happened and delayed things for a while, and when this came back around and it was moving from Vancouver to Australia, I had to talk with my wife about it. We’re a really close family and we went over it, with the possibility that we might not see each other for six months. Our kids are older now, so we decided, ‘We’ll handle it. We’ll make it work.’ It’s been tough, but we all make sacrifices.