With “The Plague” opening nationwide Friday, Joel Edgerton finds himself in an unexpected if enjoyable spot.

For Edgerton, 51, is in the midst of an Oscar campaign for “Train Dreams,” an arthouse entry that charts one man’s life in all its beauty and tragedy. A critically praised Netflix adaptation of the late Denis Johnson’s novella, it’s also in the running for a Best Picture nomination.

As for “The Plague,” it only sounds like a horror film. It’s set in a Boston boy’s water polo camp with its focus on a team of pre-teens who play what becomes a deadly game.

Edgerton, also a producer, is the team’s coach and the only recognizable name.

“We live in a world where it’s harder and harder to get small budget movies made. And there’s even more pressure on these movies to have stars attached,” Edgerton noted in a virtual interview with the film’s first-time writer-director Charlie Polinger.

“When you’ve written such a fantastic script as Charlie has, one that explores the kindness, cruelty and mob mentality of a bunch of 12- and 13-year-old kids, it doesn’t have a lot of star power you can add to that.

“Me jumping in was a way of helping get the film moving. I, more than anything, just wanted to see this movie get made. Looking back on that whole process, Charlie did an even more extraordinary job than I ever would have imagined.”

Polinger had made a short student film, “Sauna,” set at a water polo camp with a group of 13-year-old boys.

“It was,” he said, “exploring slightly different themes. Then I caught COVID and quarantined in my childhood bedroom at my parent’s house. I rediscovered journals from when I was a kid.

‘I was reading and remembering about this summer where this idea of ‘the plague’ existed. Looking at old yearbooks, all these memories came flooding back. I felt inspired to combine really personal stories and this concept of the plague in this water polo world I’d already explored.”

It’s not autobiographical. “I’m not from Boston. I’m from DC. And I did not play water polo, just some soccer and basketball.

“Water polo is,” he learned, “a very challenging sport. Having to walk around in a pool in your Speedo when you’re 12 or 13 — it feels very vulnerable, like you’re dripping and you’re exposed.

“And in this sport anything below the surface that the refs can’t see, they can’t call a foul on it.

“So punching and scratching and violence under the surface is actually built into the strategy of the game.

“To me, that felt like something really ripe, where in this underwater photography I could build this psychological soundscape for the film.”

Joel Edgerton stars in “The Plague.” (Courtesy Steven Breckon)