Homegrown (1998)

Life is good for Jack (Billy Bob Thornton), Carter (Hank Azaria) and Harlan (Ryan Phillippe), three inept ne'r-do-wells who help run master dope-grower Malcolm's (John Lithgow) flourishing marijuana plantation somewhere in northern California. But then Malcolm is suddenly bumped off by a mysterious assailant; after a moment of panic, the naive trio decide to take over the business themselves. However, their lazy days on the dope farm have ill prepared them for the high-stakes game of finding buyers for millions of dollars of contraband. As they plunge into a shadowy new world of duplicity, double-dealing and danger, they soon find that they have gotten in way, way over their heads. But driven on by increasing greed and paranoia, it's too late to back out.