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When a famed black pianist hires an Italian-American bouncer to drive him through the Deep South for a concert tour in 1962, things go awry fast — even with the help of the titular guidebook.

In the upcoming Peter Farrelly-directed road-trip drama Green Book (named after the guides black travelers used to navigate the dangers of pre-civil-rights-era segregation), Mahershala Ali (Moonlight) stars as the sophisticated Don Shirley, while Viggo Mortensen (Captain Fantastic) plays the, well, less-than-sophisticated Tony Vallelonga (better known as “Tony Lip”). And, as seen in the exclusive trailer above, Tony doesn’t exactly leap at the opportunity to chauffeur Don. “We’re an unusual combination,” Mortensen tells EW of the characters. “The odds are that I’m not going to keep the job for the whole trip, because we don’t hit it off right off the bat at all.”

Spoiler alert: They will — eventually. Green Book is based on the real-life friendship that developed between the two men after their eventful (and often tumultuous) journey. The true story helped the script — written by Farrelly, Brian Hayes Currie, and Tony’s son Nick Vallelonga — stand out from the many screenplays that crossed Ali’s desk after he won an Oscar for his performance in 2016’s Moonlight. “Green Book was a project that I kept thinking about after I had read it,” Ali says. “If you look at these two archetypes [in films], it’s so often the black guy is serving as some sort of grounding force and reality check who’s coming from a low-income or working class environment, for the wealthier, more affluent character… I really responded to the fact that it was flipped on its head the way that it was, and the fact that it was based on a real relationship.”

Credit: Universal Pictures

Though Don and Tony “couldn’t be more unlike each other,” as Mortensen puts it, Ali points out that the street-smart Tony has plenty to teach the celebrated pianist Don — and vice versa. While Tony enjoys a close-knit family, rarely ventures away from home, and feels confident in his place in society, Don struggles with feeling accepted by both the white community and the black: He’d been embraced by white audiences while on stage, but he’s treated as an inferior off it; and though he’s clearly black, he knows very little about black culture. “As a result, he feels very much alone,” Ali explains. “Those are the most interesting characters to me, the ones who have to make a way for themselves, that can only connect to portions of certain communities.”

Off-screen, Ali and Mortensen struck up their own friendship much more quickly, and long before uniting on Green Book. While on the awards circuit in early 2017, the pair — both contenders, as Ali was up for Moonlight, and Mortensen for Captain Fantastic — met each other at an industry brunch and began a lengthy conversation. In fact, Ali boarded Green Book only after seeing Mortensen had signed on to the film as well. “We had connected and just talked and hung out for about a half hour [at that awards event],” Ali admits. “But in an event like that that you’re going to be there for an hour total, that was a significant amount of time.” After all, half an hour in a ballroom can be just as meaningful as eight weeks on the road.

Watch the trailer above. Below, EW can also share this new exclusive image from the film:

Credit: Patti Perret/Universal

Green Book hits theaters Nov. 21, after having its world premiere next month at the Toronto International Film Festival.