Crank takes place the summer before and during the protagonist Kristina's junior year of high school. She is a straight-A honor roll student and decides to visit her father for three weeks. Her father is rarely home, leaving her a lot of time alone. Kristina meets a boy named Adam in Albuquerque, where she is staying with her father. Adam convinces Kristina to try crank (Methamphetamine), or "the monster", but Kristina runs away the first time she tries it. She is attacked by three men, but before anything can happen to her she is saved by Adam. An antagonist, Lince, Adam’s girlfriend, sees him comforting Kristina and jumps off of a balcony in a suicide attempt. Kristina starts a relationship with Adam, but feels guilty about Lince. When the three weeks are over, Kristina goes back to Reno, Nevada, where her mother’s house is. Kristina is now addicted to crank.
In Reno, Kristina, now calling herself Bree, meets the characters Brendan and Chase at a water-park, and they exchange numbers. They both promise her crank. Chase and Kristina begin to get closer to one another, and they begin dating, though not exclusively. Kristina goes to see the antagonist Brendan, asking for more crank. Brendan drives them both out into the woods, where they get high together, and he starts to take off her clothes. When she says no, he becomes violent, claiming that he has“waited weeks,” so she should “put up and shut up”. He then starts ripping her clothes off and rapes her. Afterwards, Brendan takes her home and makes her pay for the drugs, even though he had just violated her.
At home Kristina, still high and shaken up from the rape, writes a letter to Adam telling him she was raped. Soon though she abandons her letter and calls Chase to come over while her parents are out. Chase comes over and she tells him about Brendan before trying to persuade him to have sex with her. Chase says no, wanting to wait until she had healed from her rape. However, she does end up having sex with him later in the novel.
Kristina gets caught hitchhiking by a cop and goes to Juvenile hall, where she gets a direct connection to a meth lab in Mexico through an inmate. Once she is released from Juvenile hall, Kristina uses her mom’s Visa card to pay for the illegal narcotic, and she takes her new supply to her druggie friends on “The Avenue.” At this part of the novel, Kristina has become a drug dealer, which she describes as making her instantly more “popular.” Kristina now has a very large amount of crank on herhands, so she is getting high even more often. This leads to her becoming more irritable, causing her relationship with her mom to become even more strained. Kristina is also not showing up to classes, because she is spending all of her time getting high and dealing drugs on “The Avenue”.
The story continues with Kristina discovering she is pregnant, soon after Brendan had raped her. Kristina spends the following days going through the symptoms of drug withdrawal. During this time in the novel, she believes that Chase is the father, having had sex with Chase a couple of weeks after being raped. After going to Planned Parenthood, she realizes Brendan is actually the father. At this point in the novel, Kristina begins to struggle with deciding if she should go through with the pregnancy because she“Feared the uncertainty of choosing parenthood” and “Doubted [she] could give [her] baby away”. Kristina decides to have an abortion, but after feeling “A flutter in [her] belly,” the child moving, she decides to keep her baby. After making this decision, Kristina tells her mother andstepfather about her pregnancy, although she does not reveal who the father is. The novel continues with Kristina giving birth to a baby boy, Hunter, who is described as 'healthy'. The narrative ends with Kristina implying that she is still using drugs, but is trying to stop.