Richard Linklater's Bernie tells the tale of Bernie Tiede, a thirtysomething funeral director in Carthage, Texas, whose boundless joie de vivre and appropriately closeted homosexuality have endeared him to what seems like the entirety of the small East Texas town. One holdout: the bitter octogenarian millionaire Marjorie Nugent, widely feared as the crustiest old bitch in town— until Bernie doggedly melts her heart, forging a friendship that turns into something like marriage before Marjorie's inexhaustible bitchiness drives sweet, devoted Bernie to abruptly shut her up for good.

Bernie is based on a well-documented true story, so the notion of spoilers is questionable. Still, to tell much more of the plot would deprive viewers of the joy of discovering Bernie as a real-life tale with Hollywood-grade twists. So I'll focus on the source of so much of Bernie's charm: the cast, roughly half of whom are Hollywood professionals (including Jack Black, Shirley MacLaine, and Matthew McConaughey), while the rest are regular people—residents of Carthage who knew Bernie Tiede and Marjorie Nugent, effectively playing themselves as talking heads in a documentary.

This is a dicey-sounding proposition, blending real-life folks with movie stars as showy as Black and MacLaine, but somehow it works beautifully. It helps that the film is set in Texas, which routinely cultivates personalities on par with Nacho Libre and Madame Sousatzka; the real-life Carthage residents light up the screen like subjects in a great Errol Morris documentary, bursting forth with inimitable idiosyncrasies and self-dramatizing flair.

But playing yourself is easy compared to the task given to the professional actors, who must integrate themselves into what's being presented as a documentary. I'm happy to report that, across the board, the transition goes smoothly. Leading the charge and better than anyone is Jack Black, who gives a performance that will revolutionize your opinion of Jack Black. Any movie star can "show range" by running in the opposite direction of their bread and butter (see pretty smiley lady Charlize Theron playing unpretty frowny lady Aileen Wuornos in Monster). But the famously outsize Black does something trickier—playing an outsize personality of the sort that exists in real life. It helps that Bernie's life was itself a performance, and Black nails it, from spirited church singing to sly seductions to the deep remorse of a man made to become everything he despises. It's an unexpected triumph of a performance in a movie you will love.