Ewan McGregor is swiping through his camera roll, looking for the picture that explains why he will never grow another mustache — unless a job requires it. And even then, he’d probably argue that the character should be clean-shaven. Dalí without a mustache? Surreal.

Before our conversation, I had resolved not to ask McGregor anything about facial hair. It seems that most of the interviews he’s done to promote his terrific Paramount+ With Showtime limited series “A Gentleman in Moscow” have spent an inordinate amount of time focusing on the mustache he grew to play Count Alexander Ilyich Rostov, a Russian nobleman sentenced to house arrest in a luxurious hotel following the 1917 revolution. Over four decades (and eight episodes), the good gentleman learns to let go of formalities and appreciate simple pleasures and embrace family.

But he never shaves off that damn mustache. McGregor keeps scrolling. He’s in Atlanta, shooting “Flowervale Street,” a movie so secret that when he mentions its name, he immediately panics.

“Oh, no. I’m worried that I just blew the title.” When I tell him it’s out there, he’s relieved.

He wrapped shooting at 6:30 this morning, and here he is with me on Zoom, 41⁄2 hours later. “I’m somewhat upside down, but it’s all good,” he says. And he’s not that out of it, because when I tell him all I know about “Flowervale Street” is that David Robert Mitchell (“It Follows,” “Under the Silver Lake”) wrote and .