Screenwriting duo Seth Rogen and Evan Goldberg's follow-up to Superbad is another celebration of the underdog.

Like its predecessor, Pineapple Express is a deranged buddy comedy that casts a heroic glow on socially-awkward misfits, who would be consigned to the sidelines in any other film. Here, they are elevated to the status of demigods, rescuing fallen comrades from a burning building in their underwear or defeating a gun-toting bad guy using a humble family hatchback.

The script splices genres with giddy abandon, ricocheting between action, comedy and human drama.

On a couple of occasions, David Gordon Green's film threatens to careen out of control entirely, but there's a strangely appealing method in Rogen and Goldberg's madness, anchored by a touching camaraderie between the two leads.

Twenty-something slacker Dale Denton (Rogen) pays a visit to his lackadaisical dealer, Saul (James Franco). The dopehead offers Dale an extremely rare and potent strain of marijuana called Pineapple Express.
"It's almost a shame to smoke it," burbles Saul. "It's like killing a unicorn ... with a bomb!"

Under the influence of the heady narcotic, Dale witnesses ruthless drug lord Ted Jones (Gary Cole) murdering a rival, abetted by dirty cop Carol (Rosie Perez).

Unfortunately, Ted and Carol see Dale flee the scene and they give chase, determined to silence the witness.

Dale seeks sanctuary in Saul's apartment but quickly surmises that a roach full of Pineapple Express, left behind at the roadside, will lead Ted and Carol straight to them.

So the unlikely pals hit the road, stopping off to make sure Dale's girlfriend Angie (Amber Heard) is safe, before turning to Saul's business associate Red (Danny McBride) for help.

Pineapple Express appears an odd choice for indie director Green but he brings his quirky style to bear amid all the explosions, including a cute game of leapfrog through shards of sunlight.

The script is peppered with sparkling one-liners, like when Dale describes himself as "chill as a cucumber" or when he discovers the getaway vehicle's battery is dead. "The car just committed suicide!" laments Saul.

The bickering between the wastrels gradually mellows into mutual appreciation and affection as they lay their lives on the line to save one another from a shallow grave.

"They say don't dip your pen in company ink but I'm totally glad I dipped my pen in your ink, bro," grins Saul contentedly.

A frenetic car chase, during which the dealer attempts to kick out his shattered windscreen only to get his foot stuck, is a particularly loopy highlight.

McBride is a lively sidekick, coming to the fore during a cartoonishly violent fight between the trio. Cole and Perez sneer and snarl as the villains of the piece, peddling drugs to the masses without any concern for the repercussions.

Green's film, meanwhile, leaves you on an entirely natural high.

Film rating 4/5

Watch the trailer here