"Green Book" owes a more recent and perhaps larger debt to "Hidden Figures," which also filtered early-1960s civil rights through an inspiring true story. Yet while that hit aimed for the stars, this one focuses on a smaller, more idiosyncratic story that relies almost exclusively on its leads.Director Peter Farrelly — a name usually associated with screwball comedy — appears to be an unlikely choice to oversee such an enterprise. The film, however, tackles its subject matter with a good deal of grace, even if the script has its share of knocks and pings, especially in the early going.A key footnote involves the deeply personal nature of the project. The screenplay is credited to Nick Vallelonga — the son of Mortensen's character, Tony Vallelonga — along with Farrelly and Brian Currie, and, in flipping the "Miss Daisy" formula, spends a bit of time spinning its wheels before getting into gear.It's 1962, and Tony — basically a glorified bouncer at the Copacabana in New York, well connected among the shady swells who frequent the joint — needs a gig to tide him over financially while the club is closed for repairs.Already revealed to be a racist (he throws away glasses used by black repairmen, badmouthing them in Italian), Tony is taken aback when an opportunity arises to serve as a driver and bodyguard for Don Shirley (Ali), the brilliant leader of a musical trio. The piano virtuoso has agreed to a tour of the Deep South, but his record company fears the dangers that an African American might encounter will require the services of someone with Tony's skill set.Tony reluctantly takes the job, and is presented the Green Book, a guide to motels and restaurants that accommodate African-American travelers in the South. One needn't be clairvoyant to anticipate that the two men — as different as they could possibly be, with Tony loud and boorish, while Don is quiet and genteel — will bond over the course of their eight-week pre-Christmas trek, which separates Tony from his wife (Linda Cardellini) and kids.Tony is a bruiser who loves eating, and Mortensen has obligingly layered on pounds, "Raging Bull"-style, to fill out those undershirts. On screen, he wolfs down meals in a manner that becomes one of the film's better running gags.It's easy to wish "Green Book" itself wasn't quite so ham-fisted at times, or on-the-nose with its dialogue. But taken on its own terms, the movie possesses hard-to-resist warmth in its underlying theme, and welcome humor in the mismatched buddy dynamic — with Don attempting to make Tony less of a philistine, while the driver introduces his meticulous boss to deep-fried foods.Obviously positioned as awards bait, "Green Book," the movie, doesn't rise to that level, but the performances by Mortensen (already a two-time Oscar nominee) and Ali (a well-deserved Oscar winner for supporting actor in "Moonlight") won't be easily ignored. (Mortensen's use of a racial epithet during a panel discussion of the film, for which he apologized, in a way reinforces its timeliness.)"Dignity always prevails," Don tells Tony, whose preferred response to a slight is usually to crack heads.It's a reassuring thought, especially amid debate over how far we've come as a society in the nearly six decades since the events depicted in the film. Thanks to the hopefulness at the heart of Tony's personal journey, the very dignified "Green Book" might indeed come out a winner."Green Book" premieres in limited U.S. release Nov. 16 and expands Nov. 21. It's rated PG-13.