Jonah Hill, left, and Channing Tatum in Columbia Pictures' "21 Jump Street."

Film File - 21 Jump Street

That old advice - 'if it ain't broke, don't fix it' - is rarely listened to in Hollywood. With adaptations of old films and TV shows constantly being updated for a new generation of cinemagoers, even the best-made stories from a previous era are always fair game for a modern makeover. Some are abject failures, and some are surprising winners. This week's offering, '21 Jump Street', falls somewhere in the middle. In this action-comedy, Schmidt (Jonah Hill) and Jenko (Channing Tatum) were enemies in high school who became unlikely friends in police academy. While they may not be the best cops on the beat, they are offered a chance to turn it around when they join the police department's secret Jump Street unit, run by Captain Dickson (Ice Cube). They trade in their guns and badges for backpacks and beanies, using their youthful appearances to go undercover. Trouble is, however, teenagers today are nothing like what they were just a few years ago, and Schmidt and Jenko discover that everything they think they know about being a teenager, from sex to drugs to rock 'n' roll, is all wrong. More importantly, they both find they are still dealing with all of the adolescent problems they didn't address in their own teen years - and both will have to confront the terror and anxiety of being a teenager again and all the issues they thought they had left behind. Directed by Phil Lord and Christopher Miller, and with a screenplay by Michael Bacall, the film is based on the original television series created by legendary Hollywood producer, Stephen J Cannell. The idea for breathing new life into '21 Jump Street' as a feature film began with Cannell, whose many credits from 'The A-Team' to 'The Rockford Files' to 'The Greatest American Hero' earned him a legion of fans and admirers. '21 Jump Street' ran for five seasons, the first four on the Fox network, and starring Johnny Depp in his first major role. Five years ago, Schmidt and Jenko were high school seniors - one the awkward nerd in braces, the other the football jock and prom king. A pair of complete opposites - it has 'cute meet' written all over it. There are parts that are outright hilarious - mostly from the winning form of Hill, an actor who's become a major player since 'Moneyball'. Definitely not taking itself seriously and adding to that with passing quips to the original TV series, it is peppered with jokes that do prompt a chortle, at the least. The other plus to the film is having Cannell on board as producer - a man who, though he's ageing, knows exactly the pulse of what will and will not work in screen entertainment. 'You should never go back' is a universal phrase all of us know in different ways. In this film, we get to watch a mismatched pair test out the theory with some very funny results.