Unless there is something pretty special about one of them to differentiate it from the spate, buddy-cop comedies are a dime a dozen, one of the most tired and derivative of all subgenres. "The Heat" is that rare exception, and it's all thanks to four people: director Paul Feig (2011's "Bridesmaids"), screenwriter Katie Dippold (alum of "MadTV," making her feature debut), and, most prominently, the heaven-made comedic duo that is Sandra Bullock (2009's "The Blind Side") and Melissa McCarthy (2013's "Identity Thief"). A film that's less about plot than situations and chemistry, Feig and Dippold intentionally devise a standard police procedural before coloring it up with the explosive interactions of its entertainingly disparate, night-and-day lead characters.

Straight-laced FBI agent Sarah Ashburn (Sandra Bullock) has no significant other and her closest friend is her neighbor's cat. She performs her job strictly by-the-book and hopes to receive a long-overdue promotion from her boss, Captain Frank Woods (Tom Wilson), but first she'll have to travel from her headquarters in New Jersey to Boston to work on a time-sensitive new case. Paired with police detective Shannon Mullins (Melissa McCarthy), an abrasive loose cannon who also, it would seem, has next to no friends, Sarah realizes instantly that she and her new partner are about as different as two law enforcers can be. As their investigation into a vicious drug lord takes them from nightclubs to high-speed pursuits to gun-happy square-offs, however, Sarah and Shannon can't help but start to respect each other, seeing in each other all the things that make them more alike than they could have originally imagined.

"The Heat" is crude, riotous, and very much R-rated (Detective Mullins' vocabulary alone could make a sailor blush), but it is the unlikely yet eventually organic friendship between Sarah and Shannon where the film carves out its own noteworthy identity. The drug case goes down some rather gritty and unforeseen avenues, introducing a number of normally comedic actors in effective straight roles—former "MadTV" standout Michael McDonald (2003's "Dickie Roberts: Former Child Star") is memorably vicious and steely-eyed as wrong-element Julian—but most of this is filler, an excuse to let Sandra Bullock and Melissa McCarthy play off each other in fish-out-of-water situations. The film is enormously funny, earning full-on hearty laughs pretty consistently until it starts to lose a little steam in the home stretch. A visit to a nightclub, with Shannon stripping Sarah down in the bathroom in an attempt to make her look sexy so that she can come on to a suspect? Comic gold. Shannon's irate tirade and attempt to get out of her car when her planned parking spot is taken and she ends up wedged between two other vehicles? Hilarious physical comedy at its finest. Shannon's thick-accented Boston family (with a middle-finger-saluting matriarch played by Jane Curtin) is also cause for much amusement, especially when they size up Shannon's partner for the first time. "Boy or girl?" one of them asks. "I am female," Sarah says, a little taken aback. "You mean from the get-go?" they reply disbelievingly.

There is a dash of her "Miss Congeniality" role in FBI agent Sarah Ashburn, but Sandra Bullock has otherwise never been quite so enjoyably kooky and free-spirited as she is here. Bullock has made plenty of romantic comedies in her time, but she's never, or hardly, been given the chance to really show off her skills as an on-screen comedienne. Bullock takes her role seriously—there is palpable pain beneath her cool, collected exterior—which gives the viewer all the more reason to care about her. Not to be missed: the reveal of what one of her high school teachers signed in her senior yearbook. The yin to Bullock's yang, Melissa McCarthy mightily impresses once again with a character who is nothing like her most recent and notable past parts in TV's "Mike & Molly," 2011's "Bridesmaids," and the recent "Identity Thief." For anyone claiming that she's a one-trick pony, he or she isn't paying attention; McCarthy is a riot as the butt-kicking, salty-mouthed Detective Shannon Mullins, but the actress is also a veritable talent of real layers and underlying sensitivity.

"The Heat" goes a little long at 117 minutes—as with most comedies, energy flags a little by the third act—but that is a miniscule price to pay for the frequently dynamite goings-on. The very fact that there is a big, studio-produced summer release headlined by two women in their forties is cause enough for celebration, but the cherry on top is that the two stars put to shame plenty of performers half their age as they exhibit exactly how you get things done and come out the other side with a legitimate crowd-pleaser. Indeed, Bullock and McCarthy work deliciously as a unit. Because of them—and the savvy filmmakers on the opposite side of the camera—"The Heat" is worth running out to see for anyone who dares lament that they don't make funny movies like they used to.