Clint Eastwood’s latest movie, “The Mule,” is the story of a man who spends his twilight years running drugs for a Mexican cartel — and tries his best to escape the clutches of the authorities.

It’s certainly a challenging subject matter — one based on a true story — and Eastwood has an artistic vision like no other at the age of 88. But the filmmaker recruited some help from some other major artists to help tell his newest story.

Related: Clint Eastwood’s Latest Film — and the Stunning True Story Behind It

On top of an incredible cast that includes Bradley Cooper, Laurence Fishburne, Taissa Farmiga, Michael Pena, Allison Eastwood, Dianne Wiest, and Andy Garcia, “The Mule” also contains an original song by country music legend Toby Keith.

Keith’s new song, “Don’t Let the Old Man In,” was actually inspired by a conversation the musician had with Eastwood while the two were golfing together.

Right before Eastwood was set to begin work on “The Mule,” Keith asked what project the filmmaker would be taking on next.

Eastwood told him he would be both acting and directing in “The Mule.”

This was on the heels of Eastwood’s last film, “The 15:17 to Paris,” released earlier this year.

Shocked by the “Dirty Harry” star’s ability to keep up with such demands of the job at an advanced age, Keith asked Eastwood how he did it.

“‘I get up every day and I don’t let the old man in,’” Keith recalled Eastwood saying, according to Newsweek.

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Keith added, “And I’m like ‘Whoa, that sounds like a song.’”

It’s fitting that the tune would then end up in “The Mule,” the film at the center of that conversation between the two artists.

“Don’t let the old man in. I want to live me some more. Can’t leave it up to him. He’s knocking at my door,” sings Keith, 57, at the start of his song.

The tune is one of Keith’s most impressive. And the poetic work fits well with The Mule,” a movie Eastwood and screenwriter Nick Schenk (“Gran Torino”) have peppered with points and questions about redemption, regrets, family, pride, and moral lines.

Most of what comes out of Hollywood today is a regurgitation of old things — or franchise extensions built more to sell toys and appeal to international audiences than to challenge or entertain in any meaningful or long-lasting way.

Eastwood always manages to be an exception to the rules of modern Hollywood, as he takes on complicated and true stories that stick with audiences long after the credits roll.

With “The Mule,” he’s managed to put together not just an original movie but to inspire some original music, too.

Let’s hope Eastwood keeps up the good fight and doesn’t let that “old man in” for a long, long time. He’s a storyteller we desperately need right now.

Check out Toby Keith’s “Don’t Let the Old Man In” song below: