The calculus of 21 Jump Street shouldn't add up to a genuinely good movie. And yet it does. Somehow, an adaptation of a late-1980s FOX crime procedural that is mostly famous for launching the career of Johnny Depp and stars the only semi-likable Jonah Hill and Channing Tatum makes for one of the funniest films of the year.

Morton Schmidt (Hill) and Greg Jenko (Tatum) are former high school classmates who befriend each other several years later at the police academy. Schmidt was a painfully awkward dork/geek/nerd in high school -- Jenko dubs him "Not So Slim Shady" for his Eminem-inspired bleached hair -- while Jenko was a dimwitted, but popular jock, who gained his status, partially at least, by humiliating kids like Schmidt on a regular basis.

Schmidt and Jenko team up at the academy because they each represent half of a great police officer. Schmidt possesses the necessary intellectual gifts and Jenko the physical ones -- both severely lacking when it comes to the other's strength. Buoyed by their newfound friendship, the pair manage to graduate the academy together, presuming they are on their way to a life of being "badass motherfuckers," only to be taken down quite a few pegs when their first assignment is to patrol a local park on mountain bikes.

After an over-exuberant first bust, one in which Jenko forgets to read a suspect his Miranda rights and Schmidt is bowled over by an escaping perp, the pair wind up reassigned to 21 Jump Street, an undercover unit that infiltrates local high schools to break up drug rings and the like. Jenko and Schmidt are supposed to infiltrate and break up a ring selling a powerful and deadly drug called H.F.S. (short for Holy Fuckin' Shit).

Because of Jenko's inability to remember much beyond his own name and Schmidt's anxiety at returning to high school -- a phase of his life that was filled mostly with embarrassment -- things don't go very smoothly. Eventually, though, they make progress -- one of the big gags being that just five years later the definition of cool has been radically altered. Now, Schmidt's nerdy tendencies put him in the good graces of the popular kids, while Jenko's meatheadedness relegates him to outcast status.

From there, 21 Jump Street follows a familiar buddy-cop formula to its conclusion. The last 20 or 30 minutes felt a little stretched, though I may be alone on that. There's a predictable, yet still surprising, cameo near the end that didn't quite work for me, but I suspect did for most of the people that have seen or will see the film.

The chemistry between Hill and Tatum works throughout, though. So too do almost all of the supporting characters, from Captain Dickson (Ice Cube), the head of the undercover unit, to Ms. Griggs (Ellie Kemper), the verbally clumsy chemistry teacher with a crush on Jenko, to Eric Molson (Dave Franco), the school's top drug dealer, and a number of others in between.

Still, it's Hill and Tatum we should focus on here. Hill, like it or not, is undeniably a rising star. On the heels of his Academy Award nomination for his role in Moneyball, he showed again that he is a multi-threat, so to speak. In addition to starring in 21 Jump Street, he also co-wrote the film. Tatum, wooden as he can be at times, makes himself hard not to like (no matter what I said about him above). The big lug.

The pair, as they should, make this movie go, and it's an awfully fun ridealong.