At 71, Sam Elliott is busier than ever. He’s got four films this year: “Grandma,” “I’ll See You in My Dreams,” “Digging for Fire” and “The Good Dinosaur.” He just ended a stint on FX’s “Justified” while also working on “Grace and Frankie” and lending his iconic voice to TV commercials. He’s a standout in Paul Weitz’s “Grandma,” where his 10 minutes of screen time with star Lily Tomlin — give or take a few — galvanizes the film and exposes their characters’ history and emotional depth. In the encounter, Elle (Tomlin) and her granddaughter, Sage (Julia Garner), visit the sprawling Topanga Canyon house of Karl (Elliott), her former husband. It doesn’t take long for their history — she had an abortion without consulting Karl; she then had a one-night stand and kept that baby — to destroy any civility. Elliott, with much vulnerability and empathy, goes from welcoming host to angry jilted lover to open wound, with devastating effect.

Elliott: “I always felt that if it was on the page, the odds are you have a better chance of doing something really special. Paul’s always been an incredible writer, but I think this is the best material he’s ever written. Whether it was the character, whether it was the material or working with Lily (it was all compressed into two days) or the place up in Topanga Canyon where we shot it — it all came to bear and it was — on some level — two of my favorite days in the business.

“I think it was a combination of Lily and her being so open, it had something to do with Julia, who I’d never met, her angelic little face and what she was going through, and it had something to do with Paul. Paul gave us this great piece of material, but then he stepped back and let us go. It was a great arc, but I don’t know if I was consciously after anything special. I just tried to commit to it and be real. You know, when you get that kind of material, founded in such pain on some level, then it’s pretty easy for it to become real.

“We didn’t have any rehearsals. We went up there and walked through the scene so we’d have a leg up when we went there to shoot — you know we shot this thing in 18 days — and so time was a factor. But that moment — it was one of those pieces that spoke to me, and that particularly spoke to me in a painful way, for whatever reason, I’m not even sure.

“I remember one moment, we’d done a take or two and — I was standing on the side, kinda keeping my distance, keeping my head where I wanted it to be, and Lily leaned in to me and said, ‘You’re making me feel like a real asshole here.’

“It was a very painful thing for him, that she’d aborted his kid without conferring with him then went off and had another child with somebody else. Obviously, it was something he never got over.

“That’s where Karl was — he went from being this congenial host and happy to see her, happy to meet the granddaughter, and then as soon as the old shit, as he called it, bubbled up from the past, he just went into a dark pit. Sure was rewarding I must say.”