When news broke that Quentin Tarantino would be taking on the Manson murders in his latest film, I admittedly winced. Tarantino’s love for over-the-top gore, for painting the screen red, seemed a bad fit with the ghastly 1969 murders of several people, including the actress Sharon Tate, then married to Roman Polanski. What was entirely unexpected was that “Once Upon a Time … in Hollywood,” which had its world premiere at the Cannes Film Festival on Tuesday, would be such a moving film, at once a love letter — and a dream — of the Hollywood that was.

For a long stretch, Tarantino has fun with Rick and Cliff as they tool around Los Angeles in a cream-colored Cadillac, the radio blasting. Every so often, the friends hit a beloved landmark, like the Musso & Frank Grill on Hollywood Boulevard, where gimlets are served with sidecars and the waiters are as old as the movies themselves. At other times, Cliff drops Rick off at a studio, where the actor sweats, forgets his lines and sometimes proves he’s still got it. Cliff just gets up and goes, baby, driving around looking cooler than Steve McQueen (Damien Lewis), who briefly shows up at a party where Sharon and all the beautiful people frolic as the nights grow darker.

CANNES, France — On Tuesday, Quentin Tarantino returned with a bang and much critical love to the Cannes Film Festival with “Once Upon a Time … in Hollywood,” his finest in years. A dream of a movie, it follows a handful of Hollywood types living in smoggy, starry Los Angeles in 1969, the year the Manson family went on a frenzied murder spree. Among the victims was the actress Sharon Tate, then married to Roman Polanski. In Tarantino’s Hollywoodland, Tate and Polanski live next door to Rick Dalton (Leonardo DiCaprio), a struggling, self-doubting TV actor. His best friend is Cliff Booth (Brad Pitt), a stuntman whose glory days are probably behind him. Rick could be another Clint Eastwood; Cliff should have been another Steve McQueen.

On Wednesday afternoon, I sat down for a brief chat with Pitt and DiCaprio in a suite at the Carlton Hotel, one of the grand hotels overlooking the Mediterranean. The two were in the midst of a massive publicity operation that day, giving interview after interview. Presenting a movie at Cannes can be big business and the army of Sony Pictures employees handling this offensive had the air of people worried about fumbling the most delicate of rarities. Their famous charges, by contrast, seemed wholly relaxed. Each man was affable, direct and seemed happy to talk, but, then, they have been in the business a long time. They know how to do this.

[Read our critic’s take on “Once Upon a Time … in Hollywood.”]

Here are excerpts from the conversation.

MANOHLA DARGIS Did Tarantino show you movies to prepare for your roles?

BRAD PITT [to DiCaprio] More you than me.

LEONARDO DICAPRIO We had a screening of a multitude of B films that I had never heard of, a lot of 1960s television with actors like Ralph Meeker and Ty Hardin. These guys could have been McQueen-esque, but didn’t make the transition from black and white television, especially westerns, to career-makers like “The Great Escape.” So it was almost like a love story to them. Did they get that one opportunity? No, that may have passed them by. So let’s start talking about your character, what he might have been, what he’s struggling with as a working-class guy in the industry who has been playing the heavy from television show to television show. What that does to his psyche and his confidence?

PITT I [remember] a lot of that television. In fact [Tarantino] reminded me of much of it that I had forgotten. We did watch “Billy Jack,” some Tom Laughlin, just for fun. We were pretty much weaned on the same television and film. We talked a lot about the stuntman-actor relationship.

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