The saga of Laquan McDonald—the video, the protests, the mayor’s apology—has stirred fierce and complicated emotions in Chicago. Thursday night’s your last chance to see a documentary that will stir them further.

It helps to keep your seat for a minute or two after the movie ends and think about that black mayor and black president, and about the difference between a code of silence that conceals an assassination ordered from on high and one that merely covers up the casual death of a random black teenager who happened to act out in the wrong place at the wrong time before the wrong trigger-happy cop.