Winter's Bone, Debra Granik, 100 mins, (15), The Other Guys, Adam McKay, 108 mins, (12A)

A backwoods crime thriller so believable you can almost taste the fried squirrel

In some ways, Winter's Bone is a down-the-line detective mystery: a crook has skipped bail, a private eye looks for him in all his old hang-outs, and the habitués of those hang-outs are less than welcoming. What makes Debra Granik's tough, haunting film so memorable is its unusual setting, and the unusual detective within it.

Indeed, Ree Dolly (Jennifer Lawrence) isn't a detective at all, but a 17-year-old who lives in a tumbledown cabin in Missouri, somewhere just beyond the back of beyond. Her father spends more time in jail than at home, and her corpse-like mother is more or less catatonic, so it's left to Ree to raise her two younger siblings, which means taking them to school, cooking their dinner, and teaching them how to shoot and gut a squirrel.

When her father is arrested on drugs charges for the umpteenth time, he puts up the family property as bail, and disappears. If Ree doesn't find him within a week, she'll be homeless, so she tramps through the cold, colourless landscape and visits various wizened hicks in plaid shirts and trucker hats who might know his whereabouts. They greet her, if she's lucky, by drawling, "You got the wrong place, I 'spect." We soon come to realise that Ree is up against a crime family as merciless, hierarchical and tight-lipped as the Mafia, even if its members are based in the sticks, not the city, and none of them would be caught dead wearing a suit. The fact that Ree is part of the family herself doesn't make her relatives any less inclined to point a shotgun at her.

Adapted from Daniel Woodrell's 2006 "country noir" novel, Winter's Bone is a chillingly convincing journey into a barely civilised backwoods community, where every yard is a sculpture garden of rusting machinery and broken furniture, and where shampoo and conditioner are in short supply. What makes it so mesmeric are the heart-rending details of Ree's daily struggle to put food on the table – even if it is fried squirrel – rather than her hunt for her missing father. The mystery thickens, but it is never as interesting as her home life.

The tense, glowering Lawrence puts in a star-making performance as the indefatigable heroine, and John Hawkes is just as magnetic as her rat-faced uncle Teardrop. But it's unfair to single them out when the acting is so consistent throughout the cast. Just as the locations in Winter's Bone seem so true to life that you can believe the director simply aimed her cameras at the genuine article, all of the actors inhabit their roles so thoroughly that I found myself suspecting they were the same people in reality as they are on screen. I hope they aren't.

The Other Guys opens by introducing us to New York's top cops, Samuel L Jackson and Dwayne Johnson, a pair of ice-cool adrenalin junkies who always get their man, even if they have to destroy a million dollars' of real estate along the way. And having introduced these alpha males, the film goes on to ignore them. Instead, the story turns its attention to Will Ferrell and Mark Wahlberg, two beta males who stay in the office and do the paperwork – until, of course, they uncover the dodgy dealings of Steve Coogan's corporate fat cat, and get their own shot at glory. The casting doesn't stand up to scrutiny (since when was the square-jawed Wahlberg an "other guy"?), but it's nice to see such a novel twist on the buddy-cop formula. The suggestion is that diligent pen-pushers might be the world's real heroes, and Wall Street capitalists its villains.

It's a pity that The Other Guys can't pursue that premise for more than two minutes without getting sidetracked. Before Ferrell was a Hollywood star, he made his name as a sketch performer on Saturday Night Live, and he still sees films as strings of unrelated skits. A thriller, even a self-parodying one, needs momentum, but Ferrell keeps pressing the pause button so he can fit in some verbose riffing. That's not a problem when the digressions are funny, and sometimes they are – a brilliant set piece has two characters keeping respectfully quiet as they wrestle at a funeral – but more often I wanted to shout, "Get on with it!" Considering this hit-and-miss comedy celebrates the hard-working backroom boys over the undisciplined show-offs, it's ironic that Ferrell has the opposite idea whenever the cameras are rolling.

Next week

Nicholas Barber goes on The Town, the second Boston-set crime thriller to be directed by Ben Affleck