Desperation is an ugly thing to witness and 21 Jump Street comes drenched in it. The British definition of unfunny is dull men reciting Monty Python sketches. In the US I think it would be most other performers trying to improvise a freewheeling Will Ferrell stream of absurdity

And 21 Jump Street plays like desperate imitation of The Other Guys.

It has the same straight actor, comic actor pairing. Channing Tatum and Jonah Hill make a resistible pairing though.

A certain rigidity works for Tatum as a leading man; getting him to loosen up doesn't leave him much. He's not quite Stallone-doing-comedy bad but it does seem unnatural.

The previously rotund Hill has trimmed down considerably, and it makes him seem needy. Here you can see the first tentative steps in a campaign to lull his way to leading man status.

They play two rubbish LA cops who are demoted to a new undercover operation, infiltrating a High School to crack drugs rings.

21 Jump Street was a 1980s teen cop show that would now be entirely forgotten if it hadn't been Johnny Depp's big break.

So it is a spoof without a frame of references, a send up of nothing, the Stiller/Wilson's Starsky and Hutch film without the knitwear and car.

When the captain explains their assignment by saying that a cancelled undercover programme from the 80s is being revived because the bosses don't have any ne ideas, it's one of the best lines in the film, but you still resent it.

The sad thing is there is plenty of good, or potentially good, material here – a chase in a dual control learner car should be a riot. What kills it is the film's sheer desperation: it just keeps flinging stuff at you. If one gag doesn't work within a few seconds there's another one stomping over its crushed remains.

Let no laugh be left behind is the convention of modern Hollywood comedy. They cover all bases, mixing in everything from off-the-wall absurdity to gross toilet humour.

Here though the frantic mish-mash of styles means that the good stuff gets buried.

And whenever you think the film may be generating some goodwill, Ice Cube reappears as their potty-mouthed and savagely mirthless superior to stamp down any fledgling shoots of appreciation.

21 JUMP STREET (15)

Directors: Peter Lord and Chris Miller

Starring: Channing Tatum, Jonah Hill, Dave Franco, Brie Larson, Ice Cube and Rob Riggle

Length: 110 mins

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