The conflict between the police and communities of color
A common theme in the book is the conflict between the police and the communities of color which they frequently oppress. Throughout the novel, the unnamed young boy and his community must deal with the police, who try to quash their Black Lives Matter protest and who make them feel uncomfortable and unsafe. This conflict creates a tremendous amount of uncertainty, hatred, and apprehension amongst the members of the boy's community - as well as black communities across the country.
This conflict also engenders a lot of fear amongst the police and communities of color because of the police's killing of a young black girl, as well as the other black people they have killed.
The power of a social movement
An important, overarching theme in the book is the power of a social movement. Particularly, the power of Black Lives Matter. Black Lives Matter places an integral in the book; they organized a march for people who demanded change from the status quo of police killings and racial injustice. Their march creates a hubbub amongst the police force, who deploy in full force to quell the march.
Without Black Lives Matter, however, many would likely have stayed home, the march wouldn't have gotten so many supporters, and their ability to affect change would have been lessened.
The crippling effect of trauma acquired vicariously
One of the major themes in the book is the crippling effect of trauma acquired vicariously. Through witnessing the young girl (as well as a number of other defenseless black people) being killed by the police, the young boy (who is the unnamed narrator of the book) and other black people acquire trauma through her death. This is something that happens frequently in communities of color, most of whom, the book argues, acquire very similar trauma.