Desk-jockey CIA analyst Susan Cooper (Melissa McCarthy) is the unassuming eyes and ears behind superagent Jude Law, the svelte Bond-like asset of the CIA’s most perilous missions. When partner Brad Fine (Law) departs the scene and a second top banana (intensely self-mocking Jason Statham) goes into major snit mode, “Coop” takes up the challenge despite the objections of CIA head Allison Janney and cohort). She goes deep undercover -- in depressing dowd regalia -- to infiltrate the deadly nuke-dealer underworld and (all together now --) prevent global Boom.

We are tipped off early about the nature of this spoof: After Law dispatches a phalanx of baddies -- all in tailored bespoke suits -- he catches himself in some reflective surface and pats down his hair to its usual perfection. The change here is that many of those lurking oppo guys are tripped up, catapulted to death in calisthenic postures rarely seen, the extreme yoga of dead and dying. What we call "nefarions". Everyone has his unique limb stricture and back semi-roll. Hurts to contemplate. But we are on the move seconds later to bigger and better assignments.

For the discerning, Spy has its longeuers: Though it packs in the action stunts, the distasteful running gags (mice in the CIA subbasement, right after absurd bats flying around from some ceiling roost) and caustic one-liners we expect, director Feig falls too frequently for the expletive-laden simplistic slur to advance the story and plotline. Landing the joke shouldn’t take precedence over the protagonist’s  developed character, and one-too-many profanities becomes tiresome for those of us who would like to just enjoy the proceedings rather than cluck over the mountain of gross 4-letter pile-ons. Some of course might enjoy the slanguage.

Spy is a refreshing modal shift from the usually crude and unlikable characters played by McCarthy, whose persona is becomingly modest and unassuming, a CIA analyst-diva in a Langley vermin-ridden outpost occupied by a sea of the similarly unheralded and unrewarded. Allison Janney, in Mach-2 sergeant at arms mode, is the honcho at the Langley HQ, trying to wrest peace from a plot involving sale of a hydrogen bomb, etc.

The vulgarity quotient rises alarmingly, to uncomfortable levels, given her earlier sweetness and tractability, which shatters the kid-friendliness of this amusing romp. Still, it’s a hoot to have the avoirdupois dish it out as good as she gets, from the insanely ferocious but gorgeous Rose Byrne, playing Bulgarian diabolical plutocratess Rayna Boyanov, who must be accorded kudos (as can be said for the entire ensemble) for not cracking a smile in the face of hilarious comebacks and insult-mulligatawny from Coop and droll UK comedian Miranda Hart, McCarthy’s wingman at the Agency, a giantess. In addition to a welcome presence on the funny-femme circuit.

There is a larder duke-it-out routine McCarthy vs. Byrne, that reminds us of our fencing championship period. It’s choreographed masterfully and seemingly in real time. The thing does for pots, pans and center islands what Crouching Tiger, Hidden Dragon (2000) did for flying aerial swordplay.

Caveats include a steeplechase, between motorcycle and car, that’s too long, an occupational hazard for the genre. But we forgive the evident stunt doubles that inflect these sequences. We love the fact that McCarthy’s a dead-on shot, even if Annie Oakley couldn’t have made them, while riding in traffic, falling off, and so on.

A subtlety that is not lost on women is that though many casual insults and backhanded offense is launched, the undercover-overweight mistress of the situation doesn’t become unhinged. Instead, she gives as good as she gets, undaunted by slashing put-downs about her unflattering garments or whatever else passes for civil discourse among the privileged and slim. As with the vast success of the weight-worried Oprah, the audience will happily root for this sweet, tough, capable, unexpected non-sylph heroine.

Though the film could have a quarter-hour haircut, Jason Statham does a running gag send-up of kickass Chuck Norris-Teflon and grouchy imperviousness. If it were a Jackie Chan vehicle, Feig would show outtakes, which one suspects would have been particularly terrific.

Like 007 films, the film starts with an overdone but beguiling homage to all those husky, sexy singing paeans to male mastery, with color explosions and sliding montages in silhouette and neon contrapuntals, weapons and action figures highlit and backlit. The whole nine yards. We were in no mood to laugh, at all, but soon melted in the face of all the over the top vulgarity part-way in. Not suitable for young kids, despite the inherent draw of LOL reversals and spoofery. Had the director toned it down 5 or 10 notches, teens might have loved this. As it is, viewers should be forearmed with a cineaste’s background that lets them compare the originals in cool kill-methods and spycraft with this current iteration.

The mood is admirably sustained: McCarthy does not, as she did in both Bridesmaids and Identity Thief, irritate viewers by her crass and malign personality. But even in horrid roles that make her the butt of Hollywood notions of her ‘sin’ forn not being paradigm perfect, she manages to squeeze out laughs, though her personae have been so vulgar.

We like her for much the same reason millions liked Oprah: heart. Also, of course, outside of the major metropoli, the average female is not Bulgarian heiress “birdy” tiny. Melissa McCarthy typifies many movie-goers more than does Sandra Bullock.

Bobby Cannavale, oleaginous but less evil than the beauteous Byrne, is always fun to watch, whether on The Great White Way in a Clifford Odets revival, or in Nurse Jackie as an officious hospital director. Statham here is a pissed-off pisser, but keeps a straight face as he goes into more and more outrageous derring-do that he clearly derring didn’t.

The overall film caveat is that, despite the affability of the protagonist, her earlier sweetness is belied and negated by her blue verbiage and attitude as she warms to her nick-o’-time rescues and captures. One prefers she maintain the character of humility and self-abnegation she started with. She’s so tough when she’s tough that it suggests she could not have been so sweet to begin with, earlier.

Byrne usually plays the upright damsel, innocent, betrayed or alarmed, so this is a fun stretch. The beauteous Byrne rises to the occasion as well as did the usually likable Kate Blanchette as the evil Stepmother in Cinderella.

Quite the best part is that no matter her non-U amplitude, this comedic heroine scores in accuracy, smarts, self-deprecating humor -- succeeds where those more typical of Hollywood’s ideal “perfection” sag, big time. For just $65 million, a pittance nowadays, director Feig wrests a mostly hilarious, high-return comedy-actioner out of these ingredients.

Girth-girl, finally, gets the goods. No joke: How revolutionary.