What happens when a sports news team ready for the best days of their lives suddenly face a nightmare?

That’s the premise of “September 5” which relives how the ABC Sports crew in Munich was doing live coverage of the 1972 Olympics when Palestinian terrorists attacked Israeli athletes, killing, taking hostages and demanding a plane.

How does a sports crew become, in the blink of an eye, a news team?

“September 5” depicts those dramatic events entirely from the control room near the Olympic village where the stand-off was happening to become the world’s first terrorist attack broadcast live.

Co-written and directed by Switzerland’s Tim Fehlbaum, the film is notable for its deep-dive research and meticulous recreation of what the team saw and broadcast.

“We researched many areas, including police files. We learned early on,” Fehlbaum said in a virtual press conference with his actors, “that the media played an important role and the most important channel was ABC Sports.

“I realized when we discovered John Magaro’s character, we could tell the entire story from that perspective, from the filmmakers’ point of view. The challenge: To stay in that studio with only a monitor to the outside world.

“As a media member myself, I felt I could tell a story about this.”

“There is accuracy that in everything they tell is true,” said Peter Sarsgaard who plays ABC Sports president Roone Arledge, “including the rivalry” over whether the sports desk would continue to broadcast and tell the story or whether the news team back in the US would take control.

“It’s a question of whether people thousands of miles away should cover it and Roone,” Sarsgaard continued, “had a certain amount of ambition. But it made sense.

“I love his line, ‘They can tell us what it means later. We’re just going to cover it.’”

Sarsgaard was struck by Fehlbam’s approach. “Tim went in and found the story he wanted to present. With this level of detail — to all the equipment, the layout — he was laser-focused on the truth.”

Magaro had the good fortune that Geoffrey Mason is not just alive but was involved.

“Sometimes,” Magaro knows, “when someone exists it can almost send you on wrong path. That wasn’t the case.

“Geoff was a wealth of knowledge. That we got ABC footage is in large part due to Geoff and how revered he is in the sports broadcasting community.

“The most valuable thing he told me? Once that clock started ticking there was no time to think. When you’re in the control room you do your job —  and it wasn’t until later in a bar for a drink did they start to cry.”

“September 5” opens Jan. 17