21 Jump Street was an American police-procedural series, dead serious, I believe, about young-looking cops infiltrating high schools and youth organisations to expose drug-traffickers, child-abusers and other such predators. Johnny Depp got his first break there and has a heavily disguised, uncredited cameo role in this belated big-screen spin-off, which is played entirely for laughs. Jonah Hill (intelligent, overweight wimp) and Channing Tatum (handsome, bone-headed football star and prom king) are the high school kids who meet up again in the police academy and are then sent back as undercover cops. They are well cast and rather good, as in a knowing way is Ice Cube as their parodically irascible superior. The movie is overlong and obsessively foul-mouthed, which has, quite rightly most will think, attracted a certificate that will prevent a good many members of its target audience from seeing it.