It was a beautiful September football Sunday, when the air was electrified with the promise of another new era, another new beginning for a franchise and a tortured fan base trying yet again to keep hope alive an eternity removed from their lone Super Bowl championship.

Offensive mastermind Adam Gase calling the plays for Sam Darnold, aka the Samchise, three minutes remaining to engineer a field-goal drive that would make everyone forget about a blown 16-0 lead.

“That’s what we wanted,” Gase would say.

And this is when the Hollywood director of the wildly hyped Jets movie “Take Flight” frantically yells, “Cut! Cut! Cut!”

And changes the title of the movie to “Take Fright.”

When Darnold fails in the clutch and loses to the Bills, then has his life and career temporarily turned upside down by a bout of mononucleosis, it is as much of a Jets quarterback thing as Geno Smith getting his jaw broken with a locker room haymaker or Mark Sanchez providing his legendary Buttfumble.

Darnold comes back Sunday, better late than never, to his desperate 0-4 team against the Cowboys for what amounts to the Jets’ second opening day … minus the buzz of great expectations.

He was thrown to the wolves as a rookie in 2018 with 2019 in mind, and hiring Gase was going to make him a star.

All the talk was supposed to be about his arm and his head and his legs, instead of his spleen.

With the Patriots surging toward their 11th straight division title and the Bills emerging as a wild-card contender, it is most likely too late for the Jets.

But it is not too late for Darnold to take flight, and it is not too late for Gase to be the play-caller and quarterback whisperer he was hired to be and help Darnold make that second-year quarterback leap.

Gase didn’t come here to coach Luke Falk, no disrespect intended. He came here to coach Sam Darnold and end the Jets’ eight-year playoff drought.

This would be a good day for them to revive that sizzling summer bromance they enjoyed, and for Darnold to play with his hair on fire and get his team and his stadium rallying around him.

His mere presence is certain to energize the defense and special teams, which have played valiantly, but no one should be surprised if Darnold has to chip off some rust, even though he was given most of the first-team reps last week by an overly optimistic Gase before the doctors all but sedated him with their diagnosis.

Darnold has grown into a trusted and respected leader but should do himself a favor and resist the temptation to stand in front of his team and bark: “Spleen on me,” for obvious reasons.

Darnold will be wearing specialized padding that has eased his mind about taking hits.

Memo to Gase: Protect him anyway. At any and all cost.

Former general manager Mike Maccagnan left the offensive line cupboard much too bare before new GM Joe Douglas imported Ryan Kalil and Alex Lewis, to no avail to this point.

This is the time for Gase to design a game plan that will get the ball out of Darnold’s hands before DeMarcus Lawrence gets his hands on him.

Run like hell Le’Veon Bell would work if the Cowboys’ defense wouldn’t be waiting in ambush for him, but Gase has to figure out when and how to get the ball to his best player no fewer than 20 times, and Darnold has to remember how much of a security blanket Jamison Crowder (14 catches) was in the first season opener.

“If all 11 guys do their job on every single play, we’ll go down there and score,” Darnold said.

All 11 guys rarely do their job on every single play, especially in this operation. The only chance the Jets will have, now and in the future, is if Sam Darnold does his.