Detective Graham Waters (Don Cheadle)’s Timeline and Summary

After a car accident, Waters says people crash into each other to feel the sense of touch. During all this, he doesn't actually touch anyone.
Waters gets out of his car to check on a crime scene, and then we flash back to yesterday.
Waters and his partner, Ria, are called to a crime scene.
A white cop shot a Black man, and that Black man turned out to be another cop.
Later, during sex with Ria, Waters answers the phone to talk to his mother. He calls Ria "white" and "Mexican," neither of which is correct, which angers her.
Waters and Ria later find evidence that the dead Black cop was, in fact, engaged in illegal activity.
However, Waters is persuaded by the DA's office to suppress the evidence. The DA's office wants to be shown as strong on crime committed against Blacks by white cops.
We end up back at the beginning of the movie.
The crime scene turns out to involve Waters' brother, Peter. He's dead.
After learning that her son is dead, Waters' mother tells him it's all his fault for not bringing Peter home.
Thanks, Mom.
Everyone is sad, the end.