Who would win if characters out of an Old West drama had to fight creatures from an entirely different kind of movie?
It's a question movie-makers love to ask. So far, we've seen cowboys battle aliens from space, kung-fu assassins from China and time-travellers from the 1980s.
The hybrids are silly, either on purpose (Shanghai Noon, 2000; Back To The Future III, 1990) or by accident (Cowboys & Aliens, 2011).
Bone Tomahawk (R21, 132 minutes, opens tomorrow, 4/5 stars) is anything but silly, despite its audacious genre-bending. Here, 1970s-style cannibal grindhouse fare meets the western. Or should we say "meat"?
Death-metal drummer, novelist and first-time feature film-maker S. Craig Zahler makes his risky concept pay off by getting the basics right.
His cast is outstanding, starting with Kurt Russell as Sheriff Hunt, the leader of the hostage-rescue posse that includes Matthew Fox as Brooder, the town cad; Oscar- nominated Richard Jenkins as scatter-brained deputy Chicory and Patrick Wilson as O'Dwyer, husband of the kidnapped Samantha, played by Lili Simmons.
It is apparent that Zahler respects and loves both genres and wants his favourite flavours in one bowl. He never winks at the audience, though he can get meta.
For example, the characters are frontier-movie archetypes, but Zahler adds a twist to each one.
Chicory is the ornery old coot and comic sidekick, but there is a heartbreaking sweetness in him, born of his love for his dead wife.
The "injun scout" (Zahn McClarnon) informs the posse that if they are dumb enough to ride into certain death, he will not join them. Not for him the part of the loyal, disposable native who sacrifices himself to save his white brothers.
The mood is low-key realism. Think a less muddy, less sweary version of HBO's Deadwood (2004-2006), rather than Sergio Leone's louder spaghetti style, last seen in Django Unchained (2012).
There's also some David Cronenberg in Zahler's way of making the ultraviolent erupt during moments of calm. An axe or arrow will appear from nowhere, in the middle of a conversation, and find its mark in grisly fashion.
Killings happen without preamble, sometimes taking place off-screen. Fights are quick, matter-of-fact and result in a painful, bloody mess, as in Cronenberg's Eastern Promises (2007).
And unlike over-the-top flesh-eater homage The Green Inferno (2015), in Tomahawk there is just one scene of a human getting dressed for dinner, in a manner of speaking.
That single instance of slaughter is far more traumatising than anything in Inferno.
Zahler's cracked what is truly frightening in the idea of cannibalism: To be served, not as sacred meal in a religious rite, but as an option for casual dining. It's the final, horrific insult.
For an example of how not to blend genres, look to Krampus (98 minutes, now showing, 2/5 stars), which fuses horror, comedy and the Christmas feelgood movie into one lumpy festive package.
Based on a Tyrolean folk belief in the creature of the title, an anti-Santa who punishes the bad rather than reward the good, this film appears to fill the need for a Christmas tale with a little more bite.
But it's no Nightmare Before Christmas (1993) or Gremlins (1984). There is adult-level cynicism in the opening slow-motion montage of the melee that is last-minute gift-buying, but the rest of it struggles, the tone flip-flopping between knowingness and sincerity.
The story is seen through the eyes of a boy, Max (Emjay Anthony), who in a moment of pre-Yule anger, summons the beast, which arrives to pick off members of his extended family.
When the horror scenes kick in, the comedy grinds to a halt, and vice versa. It's a problem that happens when a movie is written as action-horror first, with a comedy writer then brought in to "punch up" jokes afterwards - all the funny is in the dialogue and nowhere else.
The dialogue in question is third-tier-sitcom quality, with jokes at the expense of redneck uncle Howard (David Koechner) and his misshapen children, each character a tiresome comedic foil and Krampus fodder.
The movie makes a moral point about accepting family as we find them, but with a tale this uneven, it is hard to care.