If only this film were … uh, dynamiter. Instead, it’s a slow-burner about a Mississippi kid who may one day erupt like a powder keg. Robbie Hendrick (William Ruffin) is the man of the house at 14, taking care of his younger brother while going to school and trying to sort out life. He gets caught stealing at school, and as punishment, he must write a reflective essay over the summer—and that’s where The Dynamiter is a little more languid than it should be. Or could be, anyway. Director Matthew Gordon and writer Brad Ingelsby have effective eyes and ears for the region, and The Dynamiter is warmly photographed, which helped make it an Independent Spirit nominee. But it never crosses the threshold and becomes truly substantial.