You’ve got to be in the right frame of mind to enjoy Hot Pursuit, which is to say desperate and trapped on a domestic flight with a dead iPad, no headphones and 87 minutes of cruising altitude to fill with something by watching it over someone’s shoulder without sound. What’s that? No sound? Don’t worry. Unless this happens to be your first movie, you’ll figure it out.

Reese Witherspoon is Cooper, a socially awkward San Antonio cop (think a Texan Tracy Flick without the ruthlessness), trying to deliver her Colombian charge Daniella (Sofia Vergara, at her volume-cranked, broken-knob worst) to Dallas before a drug lord against whom Daniella plans to testify has them killed.

Only because Witherspoon has thrown this particular gauntlet of her career down with Hulk-like force is Hot Pursuit not the worst comedy she’s ever made; it’s also not even her worst of this decade. But its blustery, blundering approach botches even the most basic pleasures of the action-comedy road picture with a pair of polar-opposite personalities. (This frequently foolproof genre is hard to screw up, but it happens.) A distaff retread of Midnight Run may have been unambitious but it wouldn’t have been this unpleasant. Instead, it’s as generic as its title, substituting character work or comic chemistry with a catastrophic litany of limp gags that would have felt dated even in 1995 had, say, Meg Ryan and Salma Hayek labored mightily to make this vehicle run.

The bummer is that the mightily talented Witherspoon and the comedienne Vergara (who can, as Modern Family viewers know, dial it down for shrewd subtlety when she has to) also produced the movie. They saw what worked about the pairing of Sandra Bullock and Melissa McCarthy in The Heat two summers ago and promptly forgot to capture any of that. Director Anne Fletcher mustered enjoyable mismatched-partner momentum in The Proposal and The Guilt Trip, but that modest magic eludes her in a film that feels like one modest cleavage-covered catfight after another.

It’s further hampered by a script from second-tier sitcom stewards John Feeney (2 Broke Girls) and David Quaintance (Joey), whose banter includes women not knowing a colloquial definition of “shotgun,” men not knowing about periods and primetime-saucy, grandma-friendly riffs on sex, drugs and lesbians. The funniest thing in it is Aussie co-star Rob Kazinsky— as a doughier, bro-ier Chris Pine type to whom Cooper takes a shine — painfully mangling his Texan accent and giving not one damn.

Whatever minimal comic ingenuity exists expires moments after the opening credits, a montage of Cooper growing up behind the Plexiglass of her cop dad’s cruiser. This upbringing puts Cooper on alert for suspicious activity but has also sealed her off from mastering even simple social graces. With her chipper-chipmunk cheeks and flaring nostrils, Witherspoon crunches her face in physical commitment a la vintage Jim Carrey; her gremlin gumption only goes so far, though, in such disposable junk.

By comparison, Vergara’s perpetual bellowing is intelligible in the sense that you can still read a sentence if only the first and last letters of its words are correct. In a lazy nod to her Modern Family character, Daniella makes vague intimations about her Colombian relatives’ violent tendencies, and the movie bizarrely plays her foghorn-loud grief over the death of her boorish husband for laughs.

The actresses corral a couple of chuckles here and there — namely in a scene where, while hiding out under a decoy deer, they bicker about what sound the animal would make. And the plot daintily nudges a tiny elbow in the media’s ribs as news reports progressively lower Cooper’s height and raise Daniella’s age. But the stars content themselves by settling comfortably into their respective stereotypes (uptight and lovable, brassy and bosomy), keeping them separated in a way that never lets them spark as a team.

Texas is a big state. By the time your plane starts its descent, all devices must be stowed and the credits roll on Hot Pursuit, you’ll certainly feel like you’ve driven the scenic route, all the way across it.