Twenty-four-year-old Hailey Cain has dropped out of the US Military Academy for reasons she won't reveal. She has had to leave Los Angeles and it would be too big a risk for her to return. Now working as a bike messenger in San Francisco, Hailey keeps a low profile, until her high school best friend Serena Delgadillo makes a call that will turn her whole life upside-down.

Serena is the head of an all-female gang on the rough streets of LA. She wants Hailey to escort the cousin of a recently murdered gang member across the border to Mexico. It's a mission that will nearly cost Hailey her life, causing her to choose more than once between loyalty and lawlessness, and forcing her to confront two very big secrets in her past...