Pineapple Express

"Dude... we should, like, make a movie about a couple of potheads. They witness a murder and, like, go on the run and are chased by bent cops and shit... then at the end, we give them loads of guns and they blow loads of shit up. It'd fucking rock... Pass the bong, dude." The stoner comedy: a movie usually conceived on drugs, filmed on drugs and best enjoyed whilst on drugs. Don't fancy watching it while high? It's like hearing a joke without the punchline. Pineapple Express is fairly typical of the genre: it's a knockabout romp that will be hilarious after a few midnight tokes, but in the harsh light of day, it's not quite the sum of its parts.

Dale Denton (Rogen) is a fat, lazy and unambitious process server - aka a professional jerk - who tricks people into receiving court orders, occasionally bangs his high school girlfriend (Mandy Lane's Amber Heard - yeah right) and smokes a lot of weed. He hits up laid-back dealer Saul (Franco) for a new strain called Pineapple Express, but while enjoying a cheeky smoke outside his next customer's house, he witnesses an execution by Rosie Perez's bent cop and Gary Cole's drug lord. Alerted to Dale's presence, and with his discarded roach their only lead, the bad guys trace the weed back to Saul - and so the chase begins. Cue the Huey Lewis theme tune.

Pineapple Express is at is best when playing to its strengths - two likeable leads, goofing off and smoking weed. Rogen and Franco give good improv, and many of the best lines sound ad-libbed - an early scene which sees the pair checking out the titular weed is one of the movie's best ("It's almost a shame to smoke it," says Saul, "It's like killing a unicorn"). Rogen dusts off his trademarked lovable loser persona, but Franco is a revelation, all needy neurosis, red eyes and crude jokes. It may be method acting, but Franco is funnier than he's ever been.

The screenplay from Rogen and writing partner Evan Goldberg is pretty basic stuff, but when they stick to what they know best (getting wasted) it's a riot. When the movie lurches into a lame action movie parody in the second half, it uses up all that goodwill. Is it supposed to be a spoof? A loving homage to the '80s chase movie a la Midnight Run? A drug-induced fantasy crossed with the worst parts of Dumb & Dumber? Apart from the inspired 'foot through windshield' car chase, the change in tone and gratuitous violence is misjudged, sapping the movie's comic energy instead of pumping it up. Superbad worked because it was written and set in high school. Pineapple Express falls short of greatness because Rogen and Goldberg know little of action, presumably aside from the countless movies they watched while high.

What's more, supplementary characters suffer under-developed storylines, leaving them with weak plot strands that'll have you longing for the return of Franco and friend. Gary Cole makes for a forgettable villain, with what seems around four minutes of screen time, while Rosie Perez's cop has little to do other than talk 'like dees'. Two squabbling hitmen, played by The US Office's Craig Robinson and Superbad's Kevin Corrigan, engage in an odd verbal sparring, alluding to off-screen incidents in dialogue that's intended to build character but comes off as waffle. Something is missing; perhaps it's a sturdier script or the lack of experience from indie director David Gordon Green.

Only rising star Danny McBride gets a decent puff of the spliff as fellow dealer - and bullet magnet - Red. Indeed, the movie's best scene is him, Dale and Saul enjoying breakfast and joyfully reminiscing about the movie's events - just three guys around a table, riffing off each other, without a shotgun or gunfight or explosion in sight. A tried-and-tested director would have seen Pineapple Express' shortcomings. The actors should have known they were coasting. Sharp viewers might not be so forgiving. But given that cast, crew and audience were and will be baked throughout, Pineapple Express just about earns itself a pass. Ali