Dale Denton is a lazy court-process clerk and stoner. He likes to visit his equally lazy dealer Saul Silver. His purpose is to purchase weed, specifically, a rare new strain called Pineapple Express. Dale becomes the only witness to a murder by a crooked cop and the city's most dangerous drug lord. He panics and drops his roach of Pineapple Express at the scene. Dale goes back to Saul to find out if the weed is so rare that it can be traced back to him. As Dale and Saul run for their lives, they quickly discover that the bad guys are hot on their trail and trying to figure out the fastest way to kill them both.