Quentin Tarantino rides to glory with Django Unchained Right now, you've got ability. But ability don't last," says gang boss Marsellus Wallace (Ving Rhames) to ageing boxer Butch (Bruce Willis) in Quentin Tarantino's single most achieved and recognised film, Pulp Fiction (1994). Tarantino has talked a lot in the years since about the shape of his career and how other directors have come unstuck; and in 2007 he seemed, with Death Proof, his half of the misconceived Grindhouse double bill and a serious misstep, to have lost it. The film, which he now acknowledges to be his worst, was the fulfilment of the geeky-video-store-clerk enthusiasm that has fuelled his appetite for cinematic sensation from the start, but without the more humane sensibility that non-genre actors such as Tim Roth, Harvey Keitel, Bruce Willis and even John Travolta had brought to his earlier work. Its violent humour rang hollow. Then came Inglourious Basterds in 2009, made at the Babelsburg Studios in Germany, which took its title (with extra jokey misspelling) from an Italian "macaroni combat" movie of 1978 by Enzo G Castellari. It was a majestic return to form: Tarantino's screenwriting was braced by a daring decision - to focus on a group of American soldiers who would constitute the "face of Jewish vengeance," worms turning against the racial oppressors with a brutality equalling that of the Third Reich. Unpredictable, ruthless plot twists carried the audience through the dizzyingly unfamiliar territory of this dark fairy tale more entertainingly than could have been hoped. Actors as good as Brad Pitt, Michael Fassbender and - supremely, as the charming villain SS Colonel Hans Landa - Oscar-winning Christoph Waltz, a magnificent Austrian actor, found more richness and sophistication in Tarantino's dialogue than one had thought possible. It was a triumph - even if the qualm-inducing meeting of grim real subject matter and headily stylised cinematic thrills proved controversial. Now Django Unchained, again featuring the 56-year-old Waltz, tackles equally controversial subject matter, slavery in the antebellum American South, and does so again with a direct nod to an Italian original, this time an actual Italian spaghetti western, Sergio Corbucci's Django of 1966. It's just the latest of 30-odd cashing-in unofficial sequels, including Django, Prepare a Coffin (1968), out this month on DVD - none of them until now featuring Franco Nero, the original Django, who has a cameo in Tarantino's movie and indeed exchanges a knowing look with Jamie Foxx, his latest successor in the role. Unchained doesn't simply follow the filone or formula of the classic (if that's the word) spaghetti western, though; as in Inglourious Basterds Tarantino creates a disturbing new fusion by bringing the thrill-based genre together with a huge historical genocidal fact. Spaghetti westerns hardly eschewed politics - the left-leaning films of Corbucci, Sergio Leone and others dismantled the moral certainties of traditional Hollywood westerns, representing the West as a place of rampant capitalism, corruption, oppression and violence. But perhaps because many were shot in Spain, the racial "other" was mostly the Mexican. As Tarantino has said, "Westerns all the time bend over backwards not to deal with slavery. So I wanted to take slavery and not ignore it, but also tell an exciting adventure story around it. The film takes one particular liberty with Corbucci's cool, amoral, violent white cowboy Django - a clear derivative of Leone's Man with No Name (Clint Eastwood) in A Fistful of Dollars (1964). For Tarantino's Django is black, a freed slave (hence Unchained) played magnificently by Foxx, who partners up with his liberator and mentor, a charming, punctilious, ruthless German dentist-turned-bounty-hunter called King Schultz (Waltz). They first spend a winter collecting bounties by slaughtering a succession of wanted bad men, then set out together on a quest to buy the freedom of Django's now-sold slave-wife Broomhilda, or Hildy. After their adventures in Texas, Tennessee, and Louisiana, they arrive in Mississippi at the grand mansion of Calvin Candie (Leonardo DiCaprio), Hildy's new owner and, for all his smooth manners, a devil in human form. The more blatant atrocities of slavery - runaways torn to pieces by hounds, the hot box, whippings - supplant the gunfights of the film's first half. Django Unchained is thus a "mash-up" of the spaghetti western - it includes landscapes and compositions as thrilling as Leone's in The Good, The Bad and The Ugly (1966), and music ripped from numerous Italian forebears, including the theme song from Django - with the less-remembered so-called "slavesploitation" films of the Black Panther era. The example Tarantino has discussed is The Legend of Nigger Charley (1972), a violent film about a slave revolt which starts on a plantation and turns into a western - calling it "a cheap, even vaguely tawdry movie. But it's satisfying... You wish it were a little better. But it really scratches the itch. And so I knew I could expand on that. Django Unchained reverses that trajectory - moving from western to steamy plantation drama. Structurally, then, The Legend of Nigger Charley is a direct inspiration. But so, more richly perhaps, is another film Tarantino has praised in the past - as one of the few "full-on, gigantic, big-budget exploitation movies" ever made by "a major studio" (Paramount) - that is, the noir veteran Richard Fleischer's divisive, extraordinarily provocative plantation melodrama Mandingo (1975), starring James Mason and Susan George, along with Ken Norton, three-time opponent of Mohammed Ali, as the huge, black Mede (short for Ganymede), a perfect athlete who is picked out as a "Mandingo fighter," for duels to the death against other slaves. The critic Robin Wood called it "the greatest film about race ever made in Hollywood." The intensely atmospheric Mandingo, containing slave revolt, whipping, incest, racial miscegenation and infanticide among other toxic ingredients, none the less amounts to a disturbing analysis of the mutually corrosive character of the institution of slavery, with its double and treble standards - what ex-slave Frederick Douglass described in 1845 as "the brutalising effects of slavery upon both slave and slaveholder." Tarantino borrows much from Fleischer - the idea of "Mandingo fighting," the Frenchman who specialises in it (Candie becomes a Francophile), the cruel white master's trusted black butler, the carriage journeys with troops of slaves to and from the plantation, the dense, oppressive language of slavery. But whereas Fleischer's bleak, sullying film ends horribly in entrapment and death for its bewildered hero, the spaghetti western element of Django Unchained keeps open for us an improbable escape in bloodily heroic style. The spaghetti western was originally developed for a new, unsophisticated, disadvantaged Italian mass audience new to cinema - and the half-Italian-American Tarantino's instinct since his video-store days has been to honour the tastes and impulses of a comparable popular viewership, primarily young and male, not necessarily white, and above all eager to be entertained - even if more self-conscious. That's probably what makes Django Unchained, beautifully shot, cunningly scripted, superbly acted, irresponsibly and viscerally thrilling as it is, such a drenching blast of unforgettable entertainment - on a crude but relatively decent moral mission, fuelled by anger at injustice, to tell some truths about American history, a "full-on, gigantic, big-budget exploitation movie" about exploitation. It lasts a leisurely sounding 165 minutes, but each of its tonally diverse episodes feels carefully calculated, an element in a long, tense journey to freedom. And its primary investment in character and performance pays off in an exhilarating sense of epic sweep, of bravura display and wit and - well, of the "ability" that Tarantino hasn't lost. Django Unchained (18) is out on Friday March 18