Crank tells the story of Kristina Snow, a high-achieving 17-year-old who lives in Albuquerque primarily with her mother, who is divorced from her father. Kristina decides one day to visit her estranged father, who also lives in Albuquerque. During her visit with her father, who is rarely home with his daughter, Kristina meets Adam. After hanging out a few times, Adam asks Kristina to try "crank" or crystal meth. She obliges but doesn't like the drug's results at first. She attempts to run away, but Adam stops her and consoles her, making his girlfriend, Lince, jealous. Her jealousy, however, manifests in an intense way: she commits suicide, scarring everyone around her who sees it.
Kristina returns home to her mother, addicted to drugs, having done it several more times before she left her father's house. Now, she is seemingly always under the influence of drugs; her new identity as the wild, reckless Bree likewise causes her life to spiral. After some time, she and Adam begin a formal relationship, which only strengthens her connection to drugs.
After returning home, she meets a young man named Brendan, whom she becomes romantically interested in despite being in a relationship with Adam. This creates tension with Adam and with those around her who don't appreciate her decision.
Her life very quickly begins to revolve around her addiction. While meeting with someone who she thinks will get her more drugs, she is raped and loses her virginity while high. She skips school, starts stealing to fund her addiction, and her grades begin to plummet. Not only that, her relationship with her mother begins to deteriorate. Kristina gets involved with yet another guy, Chase, who gets her pregnant. However, Chase eventually overdoses, leaving Kristina to deal with her pregnancy alone.
After realizing she's pregnant, Kristina decides to turn her life around. She considers an abortion but ultimately decides against it. But her battle against addiction proves very challenging for her. She wants nothing more than to stop taking drugs, but her cravings prove too powerful for her. Eventually, she gives birth to a baby boy named Hunter. She still tries to get off the drug, but she is still viciously addicted. The novel ends with a reminder that Kristina's battles are far from over.
