The Birth of a Nation Nate Parker, Armie Hammer, Aja Naomi King. Directed by Nate Parker. Rated R. Opens Friday citywide.

As the writer, director, producer and star of The Birth of a Nation, Nate Parker has complete command over his vision for the film about Nat Turner’s 1831 Virginia slave rebellion. It’s a shame, then, that Parker’s not a better filmmaker, because he’s telling an important historical story exactly the way he wants to, and reaching a wide audience with it.

The winner of both the Grand Jury Prize and Audience Award at this year’s Sundance Film Festival, Birth is often powerful but just as often clumsy and heavy-handed, with nowhere near the artistry or grace of a movie like 12 Years a Slave. In its depiction of Turner’s life, it follows a predictable biopic formula, with lazy movie shorthand (a character coughs blood into a handkerchief in one scene and is dead in the next), one-dimensional supporting characters and rushed montages indicating the passage of time.

Parker’s depiction of the brutality of slavery is so intense that it borders on cartoonish, and almost all the supporting performances are extremely broad. But Parker’s own lead performance as Nat is layered and often surprising, as is Armie Hammer’s performance as plantation owner Samuel Turner, whose relationship with Nat is far more complex than the perfunctory dynamic between Nat and his wife Cherry (Aja Naomi King). Nat and Samuel grow up together, and Samuel’s parents take Nat in and teach him to read, first exposing him to the Bible. Years later, Nat is preaching the word of God to his fellow slaves, and Samuel treats him with as much respect and compassion as is possible between a master and a slave. At the same time, Samuel isn’t immune to financial pressures or the prevailing attitudes of his era, and he doesn’t hesitate to exploit Nat’s oratory skills for his own monetary gain, sending Nat off to preach at other plantations whose harsh owners want to pacify their slave populations.

Parker conveys Nat’s gradual religious awakening with dignity and ferocity, and the movie’s portrayal of faith is provocative, as Nat goes from preaching obedience to fomenting violent rebellion, all inspired by his connection to God. As a writer and director, though, Parker doesn’t seem to trust himself as an actor, and he adds in belabored dream sequences, childhood flashbacks and awkward symbolism to overemphasize Nat’s disillusionment and rage. Likewise, the supporting characters serve little function other than to suffer and/or perpetrate injustices that fuel Nat’s hunger for rebellion. Once that rebellion comes, Parker presents it with visceral force, and the lack of subtlety in the filmmaking highlights just how ugly the conflict becomes. Parker bludgeons the audience the way his main character has been bludgeoned all his life.