Inside Josh Charles’ day working with ‘damn cool’ Taylor Swift on ‘Fortnight’ music video

It was beyond his “Wildest Dreams.”

Josh Charles, the actor best known for “The Good Wife,” recently starred with Ethan Hawke in Taylor Swift’s music video for “Fortnight,” which dropped April 19.

When Swift reached out to him about it, he took an understandable course of action: “First of all, make sure I wasn’t being Punk’d,” Charles told The Post while promoting his new Hulu show “The Veil” (premiering Tuesday).

“Then, I was very excited,” he added.

“I thought it was a cool idea she had, and I was really touched by it. Ethan and I just had one hell of a day,” Charles said of his “Dead Poets Society” co-star. “It was a great opportunity for us to spend some time together and laugh. It was great. I was super excited about it. And it was really cool for my kids,” he added, referring to his 10-year-old son and 6-year-old daughter with his wife, Sophie Flack.

In the music video for Swift’s song, off her newly released album “The Tortured Poets Department,” Swift wakes up in what appears to be an asylum.

Post Malone, who is featured on the song, is revealed to be an old flame.

Charles and Hawke play scientists working in a lab. Malone later swoops in to save Swift from the lab experiments.

Swift wrote on Instagram shortly after the video’s release that Malone “blew me away on set as our tortured tragic hero and I’m so grateful to him for everything he put into this collaboration … I’m still laughing from getting to work with the coolest guys on earth, @ethanhawke and @mrjoshcharles (tortured poets, meet your colleagues from down the hall, the dead poets).”

Charles’ and Hawke’s character names from the 1989 film are written on their lab coats in the video.

“We stay in touch quite a bit,” Charles told us of Hawke. “I see him and we text quite a bit. I had done a voice for his documentary on Paul Newman and Joanne Woodward [“The Last Movie Stars”]; I had voiced a character or two. But we realized we actually hadn’t worked together and been on camera together” in a long time.

“So we were laughing about that. By the time we got [to the video shoot], it was pretty late, and we were tired and goofy and giggly. We had a lot of laughs. It was all good feelings.”

About working with Swift, he said, “Honestly, what’s most surprising is how approachable she was, and how damn cool she was. I don’t know if I expected her not to be, but I just think that was such a pleasant surprise.”

He added: “She’s at the top of the world right now, and just felt like such a grounded, cool human. It was nice to talk to her and spend a day working and laughing.”

Swift also directed the video. “She was a fantastic director, too, my kind of director, knows what she wants, and then you don’t have to do it 18 times,” he said.

“‘We got it, we can move on.’ I love that kind of confidence with directors.”

“I was just impressed by the whole scope of it. I was already a fan, I’m even a bigger fan now. That’s how I felt, her class and the way that she treated us– it doesn’t take that much, but when people treat you like that, you have more appreciation,” he continued. “It was a great lesson for me, too, just to realize in my own small way, it doesn’t take that much more to connect with people and go the extra mile. She’s very good at that, aside from being an incredibly talented artist.”