At the end of Crank, Kristina stands on the front porch, listening to her baby cry inside the house and thinking about her struggles as a teenage parent and continued desire for crank. "Sometimes I want to curl up in a ball and roll away," she says. "Sometimes I just want to die. I only know one thing that can make me laugh again" (Happy Endings.4). She says that no matter how much she wants to get away from it, the monster will never truly let her go—and "today, it's calling me out the door" (Happy Endings.5). Yikes. Is she going to make it?
This is the kind of cliffhanger ending that borders on unfair. It assaults us with numerous questions. Does Kristina go off in search of drugs? Does she turn around and go back in the house? Are her old habits really dead? There's definitely some serious ambiguity going on here—while we hope Kristina will do the responsible thing and go tend to Hunter's needs, we also know there's just as much of a possibility that she'll head off in search of Robyn or someone else who can supply her craving.
It's actually pretty significant that the final moments of the book take place on Kristina's porch, an interim location between the two choices facing her. On one hand, she can go back inside and care for her son, while on the other, she can go down the stairs and revisit the darkness of her addiction. There's only one surefire way to know which way she heads next, though, and that's to get your hands on a copy of Glass, the sequel to Crank.