Although thoroughly marijuana-soaked and wholly concerned with the relationship between a drug dealer (James Franco's Saul) and his client (Seth Rogen's Dale), Pineapple Express is fairly well removed from familiar "mission" movies like Dude, Where's My Car? or Harold and Kumar go to White Castle, in which stoned characters bounce between misadventures with vermilion eyes and hearty appetites. This is, instead, a balls-out, adrenalin-fuelled action flick with a THC twist - it's more 48 Hours than Still Smokin' - and relatively disinterested in the well established tenants of its, ahem, trailblazers.

When process server Dale witnesses a police assassination, he drives off, inadvertently dropping an incriminating roach in the street. This, invariably, leads a mob boss (the evergreen Gary Cole) to his doorstep and pits him against an army of corrupt law enforcers and criminal lowlifes. Dale then convinces Saul to hit the road with him, and along the way they pick up Danny McBride's drug middleman Red, whose innate silliness counterbalances some of the guns and blood going on around them.

Throughout, Dale works hard to convince his still in high school girlfriend, Angie (Amber Heard), that he's a good guy and a good influence, but for all its action sequences and romantic subplots, Pineapple Express is a film conceived as an exploration of the dealer-buyer relationship. As that relationship subsequently moves through a crucible of police corruption, government conspiracy, thousands of shotgun shells and a broken heart, the film gets lovingly caught up in the joys of smart-arse repartee and physical comedy and momentarily loses its sense of purpose. However, each such wrinkle helps the film stray further from its marijuana roots to become defined by its merits rather than its genre.