Hidden meaning behind the ‘Mission Impossible’ theme — and other secrets of the classic spy track

They are four notes that changed the action game: “Dum dum da da.”

That is the musical motif that instantly set the suspenseful stage for many a thrilling spy adventure as the theme song of “Mission: Impossible” — both the series and Tom Cruise’s film franchise that is supposedly coming to a close with the “Final Reckoning” installment that opened in theaters on Friday.

But those two long notes, followed by two short ones had a secret message hidden in them by composer Lolo Schifrin, who wrote the legendary theme for the CBS TV series that ran from 1966 to 1973. With the “dash dash” standing for “M” and the “dot dot” for “I,” together they mean “MI.”

Schifrin’s jazzy spy motif has not just survived but thrived through many a dangerous mission over the years, sending Cruise’s Ethan Hunt off running to do the impossible — yet again — in the new film.

“Really, I had no idea this theme would catch on like it did,” Schifrin told the Washington Post. “It was some kind of magic connection with people.”

Here, we uncover some other trivia secrets of “Mission: Impossible” theme song.

Schifrin wrote the theme without seeing any of the series.

“All I knew was that it would start with the lighting of a fuse,” Schifrin told the Washington Post about the series’ iconic opening in 1996.

Otherwise, Schifrin had “complete freedom” in the creative process. “I just thought about the promise of adventure and excitement, with a little sense of humor,” he said.

Under an impossible deadline, he completed his mission in minutes.

“I sat at my desk and wrote that theme in exactly one and a half minutes,” he told Emmy magazine in 2016. “It was not inspiration; it was a need to do it. It was a little mission — impossible!”

“The whole thing — including the chorus, the bongos, everything you hear — took me maybe three minutes.”

“Orchestration’s not the problem for me,” Schifrin told The Post in 2017. “It’s like writing a letter. When you write a letter, you don’t have to think what grammar or what syntaxes you’re going to use, you just write a letter. And that’s the way it came.”

The theme song has a rare rhythm.

Schifrin used the 5/4 time signature for the theme song, rather than a standard 4/4.

“I wanted to avoid a predictable beat, and the only exposure most Americans would have to 5/4 rhythm was Dave Brubek’s ‘Take Five,’” Schifrin told the Washington Post.

The song charted on the Billboard Hot 100 in 1968.

As a single, the theme was on the Hot 100 hit for 14 weeks in 1968, reaching a peak of No. 41.

Grammy loved — and awarded — it.

The “Mission: Impossible” theme song won the Grammy for Best Instrumental Theme in 1968, while Schifrin also took the gramophone for Best Original Score Written for a Motion Picture or a Television Show.

And in 2017, the 1967 recording of it was inducted into the Grammy Hall of Fame.

U2’s Adam Clayton and Larry Mullen Jr. reimagined it.

For the first “Mission Impossible” film in 1996, directed by Brian DePalma, U2 bassist Clayton and drummer Mullen revamped the theme into an electronic dance track. The pair earned a Grammy nomination for Best Pop Instrumental Performance.

“It’s a shocking transition, and I like it,” Schifrin told the Washington Post.