Malcolm McDowell Says Working with Ex Mary Steenburgen Again Felt Like 'Putting on a Pair of Comfortable Slippers'

Malcolm McDowell and Mary Steenburgen are reuniting on the big screen.

More than three decades after McDowell, 81, and Steenburgen, 71, divorced in 1990 after 10 years of marriage, the former couple are acting together, in the upcoming Western Last Train to Fortune, for the first time since their 1983 film Cross Creek.

McDowell tells PEOPLE working with Steenburgen again (they first met while making their 1979's Time After Time) felt perfectly comfortable.

"I didn't really know how it would be, but from the first moment we started rehearsing it was like putting on a pair of comfortable slippers," he says. "I just say that with a certain amount of reverence that our chemistry was where it was way back in the day when we did Time After Time all those years ago, which was a wonderful experience for both of us."

"We both kind of fell in love on that film, but we're both now with other partners and very happy," he adds.

Steenburgen has been married to Ted Danson since 1995, while McDowell married wife Kelley Kuhr in 1991. "Just the working experience was so comfortable and so 'I've got your back,' that kind of thing. Whatever you want to do, try."

Last Train to Fortune, directed by Adam Rifkin, also stars the late Bill Paxton's son James Paxton, plus Bernadette Peters and Laura Marano. McDowell plays a schoolteacher who travels across the Old West around the 1870s with an outlaw (Paxton, 30) after initially missing his train to a new town to take up a job.

McDowell says the film's producers wanted him to call Steenburgen and recruit her for the movie himself, but he ultimately asked someone else from the production to make the call.

"She read it and she said, 'Yes, I'd love to do it,' " he says, noting that Steenburgen has "a very important scene" at the end of the film. "When I went on set, she just looked at me and said, 'Why didn't you call me?' I remember saying to her, 'Well, you are here, aren't you? So it doesn't matter who called.' "

He also says Steenburgen, with whom he shares daughter Lilly, 43, and Charlie, 40, gave important notes on set that helped her and McDowell stage their scene together that McDowell had not previously thought about.

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"She said, 'Well, before you get here, I'm teaching the kids, but I can't be a very good teacher, can I? If we've hired you to come and teach. Otherwise I would do it myself,' " he recalls. "I went, 'Well, that is a good point. You better not be teaching 'em too well.' So just little things like that."

He adds, "She's really great. It was lovely."

Last Train to Fortune is expected to debut this fall.