In the wake of the police shooting of a black teenager, Los Angeles is as tense as it's been since the unrest of the early 1990s. But Grace Park and Shawn Matthews have their own problems. Grace is sheltered and largely oblivious, living in the Valley with her Korean-immigrant parents, working long hours at the family pharmacy. She's distraught that her sister hasn't spoken to their mother in two years, for reasons beyond Grace's understanding. Shawn...